Alliteration gives the poem rhythm, musicality, and meaning. Take a look at the opening lines, for instance:
Moon marked and touched by sun
my magic is unwritten
The muted /m/ alliteration here perhaps suggests the muffled quality of the speaker's "unwritten," or unappreciated, "magic."
Listen, too, to the intense alliteration in this passage from the second stanza:
and still seeking
my sisters
witches in Dahomey
wear me inside their coiled cloths
The sibilant /s/ sounds in "still seeking / my sisters" draw whispery attention to the important idea of Black sisterhood, while the tight /c/ sounds of "coiled cloths" sound a lot like what they describe: the intricate curls of robes or headscarves. The /w/ of "witches" and "wear," meanwhile, adds some plain old musical intensity to this striking image of a sisterly group of Black witches communicating across generations.
In the last lines of the poem, meanwhile, the /w/ alliteration in "woman" and "white" highlights the way that the word "woman" is all too often assumed to mean "white woman": the poem suggests that women of color, and Black women in particular, are often treated as non-women, left out of a lot of so-called feminist "progress."