As explanation for men's attraction to her, Maya Angelou's speaker describes the movements of her individual features and the poetry of her motions. These, she declares, are the reasons for her being a "phenomenal woman."
In the first stanza, the speaker notes that pretty women are curious about her secret and ask her how she is able to be so attractive to men. However, when she explains that it is not just her features, "They think I'm telling lies." Nevertheless, she says that her "certain something" that is indefinable is found in the style of her movements and the grace of these movements:
It's in the reach of my arms,
The span of my hips,
The stride of my step,
The curl of my lips...
The swing in my waist
Then, too, she employs imagery to describe the unique features of her body:
It's the fire in my eye,
And the flash of my teeth
The speaker then further explains that she has an inner mystery reflected by her body and movements, which she describes in metaphoric terms:
It's in the arch of my back,
The sun of my smile...
The grace of my style.
Calling herself "a woman / Phenomenally," the speaker adds that men cannot define what it is that draws them to her. For she has an inner mystery, and even when she makes an effort to show it to them, the men say that they still cannot see from what features come her mysterious attractiveness. While the men in the poem look for something concretely physical as the cause of the speaker's attractiveness, the speaker understands that her feminine power comes from an inner source reflected in a combination of physical attributes.