The first stanza of this poem reads like a love letter to a continent. Africa, transformed into the luscious body of a woman, turns out to be gorgeous. It turns out, though, that this "woman" is actually a continent. It's sort of like thinking of the US as "Lady Liberty."
Angelou starts the poem with such a detailed description of Africa to help us visualize what slavery has done to the continent.
Africa's description doesn't necessarily change over the course of the poem, but her strength undergoes transformation. Our speaker tells us at the end that she is "rising" and that her strides are getting longer.