Rambam devotes a full chapter to Olam HaBa, describing it as the disembodied enjoyment of the Divine light by the soul, and explicitly states it is beyond human imagination. He distinguishes it from Gan Eden and from resurrection, presenting a clear hierarchy of afterlife concepts.
הָעוֹלָם הַבָּא אֵין בּוֹ גּוּף וּגְוִיָּה אֶלָּא נַפְשׁוֹת הַצַּדִּיקִים בִּלְבַד בְּלֹא גּוּף כְּמַלְאֲכֵי הַשָּׁרֵת. הוֹאִיל וְאֵין בּוֹ גְּוִיּוֹת אֵין בּוֹ לֹא אֲכִילָה וְלֹא שְׁתִיָּה וְלֹא דָּבָר מִכָּל הַדְּבָרִים שֶׁגּוּפוֹת בְּנֵי אָדָם צְרִיכִין לָהֶן בָּעוֹלָם הַזֶּה. וְלֹא יֶאֱרַע דָּבָר בּוֹ מִן הַדְּבָרִים שֶׁמְּאָרְעִין לַגּוּפוֹת בָּעוֹלָם הַזֶּה. כְּגוֹן יְשִׁיבָה וַעֲמִידָה וְשֵׁנָה וּמִיתָה וְעֶצֶב וּשְׂחוֹק וְכַיּוֹצֵא בָּהֶן. כָּךְ אָמְרוּ חֲכָמִים הָרִאשׁוֹנִים (גמרא ברכות יז א) "הָעוֹלָם הַבָּא אֵין בּוֹ לֹא אֲכִילָה וְלֹא שְׁתִיָּה וְלֹא תַּשְׁמִישׁ אֶלָּא צַדִּיקִים יוֹשְׁבִים וְעַטְרוֹתֵיהֶם בְּרָאשֵׁיהֶן וְנֶהֱנִין מִזִּיו הַשְּׁכִינָה". הֲרֵי נִתְבָּרֵר לְךָ שֶׁאֵין שָׁם גּוּף לְפִי שֶׁאֵין שָׁם אֲכִילָה וּשְׁתִיָּה. וְזֶה שֶׁאָמְרוּ צַדִּיקִים יוֹשְׁבִין דֶּרֶךְ חִידָה אָמְרוּ. כְּלוֹמַר הַצַּדִּיקִים מְצוּיִין שָׁם בְּלֹא עָמָל וּבְלֹא יְגִיעָה. וְכֵן זֶה שֶׁאָמְרוּ עַטְרוֹתֵיהֶן בְּרָאשֵׁיהֶן כְּלוֹמַר דַּעַת שֶׁיָּדְעוּ שֶׁבִּגְלָלָהּ זָכוּ לְחַיֵּי הָעוֹלָם הַבָּא מְצוּיָה עִמָּהֶן וְהִיא הָעֲטָרָה שֶׁלָּהֶן כָּעִנְיָן שֶׁאָמַר שְׁלֹמֹה (שיר השירים ג יא) "בָּעֲטָרָה שֶׁעִטְּרָה לּוֹ אִמּוֹ". וַהֲרֵי הוּא אוֹמֵר (ישעיה לה י) "וְשִׂמְחַת עוֹלָם עַל רֹאשָׁם" וְאֵין הַשִּׂמְחָה גּוּף כְּדֵי שֶׁתָּנוּחַ עַל הָרֹאשׁ. כָּךְ עֲטָרָה שֶׁאָמְרוּ חֲכָמִים כָּאן הִיא הַיְדִיעָה. וּמַהוּ זֶה שֶׁאָמְרוּ נֶהֱנִין מִזִּיו הַשְּׁכִינָה. שֶׁיּוֹדְעִים וּמַשִּׂיגִין מֵאֲמִתַּת הַקָּדוֹשׁ בָּרוּךְ הוּא מַה שֶּׁאֵינָם יוֹדְעִים וְהֵם בַּגּוּף הָאָפֵל הַשָּׁפָל: וְכַמָּה כָּמַהּ דָּוִד וְהִתְאַוָּה לְחַיֵּי הָעוֹלָם הַבָּא שֶׁנֶּאֱמַר (תהילים כז יג) "לוּלֵא הֶאֱמַנְתִּי לִרְאוֹת בְּטוּב ה' בְּאֶרֶץ חַיִּים". כְּבָר הוֹדִיעוּנוּ הַחֲכָמִים הָרִאשׁוֹנִים שֶׁטּוֹבַת הָעוֹלָם הַבָּא אֵין כֹּחַ בָּאָדָם לְהַשִּׂיגָהּ עַל בֻּרְיָהּ וְאֵין יוֹדֵעַ גָּדְלָהּ וְיָפְיָהּ וְעָצְמָהּ אֶלָּא הַקָּדוֹשׁ בָּרוּךְ הוּא לְבַדּוֹ. וְשֶׁכָּל הַטּוֹבוֹת שֶׁמִּתְנַבְּאִים בָּהֶם הַנְּבִיאִים לְיִשְׂרָאֵל אֵינָן אֶלָּא לִדְבָרִים שֶׁבַּגּוּף שֶּׁנֶּהֱנִין בָּהֶן יִשְׂרָאֵל לִימוֹת הַמָּשִׁיחַ בִּזְמַן שֶׁתָּשׁוּב הַמֶּמְשָׁלָה לְיִשְׂרָאֵל. אֲבָל טוֹבַת חַיֵּי הָעוֹלָם הַבָּא אֵין לָהּ עֵרֶךְ וְדִמְיוֹן וְלֹא דִּמּוּהָ הַנְּבִיאִים כְּדֵי שֶׁלֹּא יִפְחֲתוּ אוֹתָהּ בַּדִּמְיוֹן. הוּא שֶׁיְּשַׁעְיָהוּ אָמַר (ישעיה סד ג) "עַיִן לֹא רָאָתָה אֱלֹהִים זוּלָתְךָ יַעֲשֶׂה לִמְחַכֵּה לוֹ". כְּלוֹמַר הַטּוֹבָה שֶׁלֹּא רָאֲתָה אוֹתָהּ עֵין נָבִיא וְלֹא רָאָה אוֹתָהּ אֶלָּא אֱלֹהִים, עָשָׂה אוֹתָהּ הָאֱלֹהִים לָאָדָם שֶׁמְּחַכֶּה לוֹ. אָמְרוּ חֲכָמִים כָּל הַנְּבִיאִים כֻּלָּן לֹא נִבְּאוּ אֶלָּא לִימוֹת הַמָּשִׁיחַ אֲבָל הָעוֹלָם הַבָּא עַיִן לֹא רָאָתָה אֱלֹהִים זוּלָתְךָ: זֶה שֶׁקָּרְאוּ אוֹתוֹ חֲכָמִים הָעוֹלָם הַבָּא לֹא מִפְּנֵי שֶׁאֵינוֹ מָצוּי עַתָּה וְזֶה הָעוֹלָם אוֹבֵד וְאַחַר כָּךְ יָבוֹא אוֹתוֹ הָעוֹלָם. אֵין הַדָּבָר כֵּן. אֶלָּא הֲרֵי הוּא מָצוּי וְעוֹמֵד שֶׁנֶּאֱמַר (תהילים לא כ) "אֲשֶׁר צָפַנְתָּ לִּירֵאֶיךָ פָּעַלְתָּ" וְגוֹ'. וְלֹא קְרָאוּהוּ עוֹלָם הַבָּא אֶלָּא מִפְּנֵי שֶׁאוֹתָן הַחַיִּים בָּאִין לוֹ לָאָדָם אַחַר חַיֵּי הָעוֹלָם הַזֶּה שֶׁאָנוּ קַיָּמִים בּוֹ בְּגוּף וְנֶפֶשׁ וְזֶהוּ הַנִּמְצָא לְכָל אָדָם בָּרִאשׁוֹנָה:
In the world to come, there is no body or physical form, only the souls of the righteous alone, without a body, like the ministering angels. Since there is no physical form, there is neither eating, drinking, nor any of the other bodily functions of this world like sitting, standing, sleeping, death, sadness, laughter, and the like. Thus, the Sages of the previous ages declared: "In the world to come, there is neither eating, drinking, nor sexual relations. Rather, the righteous will sit with their crowns on their heads and delight in the radiance of the Divine Presence." From that statement, it is clear that there is no body, for there is no eating or drinking. [Consequently,] the statement, "the righteous sit," must be interpreted metaphorically, i.e., the righteous exist there without work or labor. Similarly, the phrase, "their crowns on their heads," [is also a metaphor, implying] that they will possess the knowledge that they grasped which allowed them to merit the life of the world to come. This will be their crown. A similar [usage of this metaphor was employed by] Solomon [Song of Songs 3:11]: "The crown with which his mother crowned him." [Support for the concept that this does not refer to a physical crown can be brought from the prophecy, Isaiah 51:11]: "Eternal joy will be upon their heads." Joy is not a physical entity which can rest on a head. Similarly, the expression "crown" used by the Sages [refers to a spiritual concept], knowledge. What is meant by the expression, "delight in the radiance of the Divine Presence"? That they will comprehend the truth of Godliness which they cannot grasp while in a dark and humble body. How very much did David desire the life of the world to come as implied by [Psalms 27:13]: "Had I not believed that I would see the goodness of God in the land of the living!" The Sages of the previous generations have already informed us that man does not have the potential to appreciate the good of the world to come in a full sense nor can anyone know its greatness, beauty, and power except God, alone. All the beneficence which the prophets promised Israel in their visions are only physical concerns which Israel will appreciate in the Messianic age when dominion [over the world] will return to Israel. However, the good of the life of the world to come has no comparison or likeness, nor was it described by the prophets, lest with such a description, they diminish it. This [was implied] by [Isaiah's (64:3)] statement: "No eye has ever seen, O God, except for You, what You will do for those who wait for You;" i.e. the good which was not perceived by the vision of a prophet and is perceived by God alone, this was created by God for those who wait for Him. The Sages declared: "All the prophets only prophesied about the Messianic Age. However, regarding the world to come - `No eye has ever seen, O God, except for You.' The Sages did not use the expression "the world to come" with the intention of implying that [this realm] does not exist at present or that the present realm will be destroyed and then, that realm will come into being. The matter is not so. Rather, [the world to come] exists and is present as implied by [Psalms 31:20: "How great is the good] that You have hidden... which You have made...." It is only called the world to come because that life comes to a man after life in this world in which we exist, as souls [enclothed] in bodies. This [realm of existence] is presented to all men at first.