Can you summarize the poem, "The Phenomenal Woman" by Maya Angelou?

Maya Angelou's "Phenomenal Woman" describes a woman who has a certain je ne sais quoi. This is a French expression used to convey a quality that one senses about another without being able to exactly describe it.
In Angelou's poem, the speaker initially states that prettier women than she "wonder where my secret lies" because they do not know how to define it. Indeed, the speaker possesses a quality that attracts men without objective explanation because she is not "cute or built to suit a fashion model's size." Yet, while others may not be able to define her feminine magnetism, the speaker feels that she can. Put simply, she defines herself:

I'm a womanPhenomenally.Phenomenal woman,That's me.

In the second stanza, the speaker expands upon her definition of herself as a "Phenomenal woman" who causes men to stand or even kneel in awe of her when she enters a room. Some even "swarm" around her as bees to a hive. This occurs because she has a "fire" in her eyes, a "flash" of her teeth, a "swing" in her waistline, and a "joy" to her feet as she enters. All of these movements catch the eyes of men; nevertheless, she cannot be defined by these men who watch her because she is "a woman/Phenomenally."
In the brief third stanza, the speaker confirms her description of herself:

Phenomenal woman,That's me.

Finally, in the fourth stanza, the speaker notes that men themselves are puzzled by what it is about her that they perceive when they see her. For, they cannot solve her "inner mystery" even when she tries to "show them." Truly, then, it is just that je ne sais quoi --that certain something--that makes her all woman:

It's in the arch of my back,The sun of my smile,The ride of my breasts,The grace of my style.I'm a womanPhenomenally.

Not just one who possesses certain very seductive womanly qualities, the speaker is entirely a woman because of her self-confidence and comfort in her appearance. She knows that she does not have perfect features, but she uses every part of her womanly self to her advantage. For this reason, she is a "Phenomenal woman"--a woman whose summation of qualities creates the "phenomenon" of beguiling men.