In the these two concluding parts of the Prolegomena, Kant doesn't add anything new to his account of metaphysics. Instead he stands back to assess its significance, with a focus on content in the first and method in the second.
Much of the conclusion—the last third or so of §57 and all of §58—concerns the idea of God. Although Kant’s life doesn’t seem to intrude much into his thought, one bit of biographical information is often cited, and it seems relevant here. Kant’s parents were associated with a religious movement in 18th century Germany known as “Pietism.” The central thrust of this movement was a rejection of any intellectualization of religion; that is, it seems to have been an attempt to make the attitude indicated by the phrase ‘simple piety’ central to religion. Although Kant is himself anything but “anti-intellectual,” he does say in his preface to the Critique, “I had to deny knowledge in order to make room for faith” (B19).
• The initial discussion of the conclusion (§§57-58, pp. 85-94) is centered on the distinction between “limits” and “bounds” that Kant makes on p. 86 (Ak. 352) and develops on p. 88 (Ak. 354) just before beginning his discussion of God (on p. 89). That discussion contrasts what he has to say with “deism,” a view of God as simply supreme being and creator, and “theism,” in which God is regarded as having a continuing involvement with the world and as being in some sense a person (hence the charge of “anthropomorphism,” of conceiving God as having human attributes). Kant describes his view (at the end of §57) as a “symbolic anthropomorphism,” in which God is thought of as if acting from understanding and will.
• In the remainder of the conclusion, §§59-60 (pp. 94-98), Kant returns to a more general consideration of metaphysics, first by way of furter discussion of limits and bounds and then by way of speculation about the “natural ends” of our metaphysical “disposition.”
• In his “solution” to the problem of how metaphysics is possible (pp. 99-104). Kant notes that metaphysics on his view need not await future discoveries (since it is independent of experience), and he distinguishes its proper method from both a recourse to claims of probability and a reliance on “common sense.”