Don't you mean the short story, by Maya Angelou? In this story, Marguerite (Maya) is embarassed because her Momma talkes to a refined black woman named Sister Flowers with incorrect grammar. For example, she says, "How you, Sister Flowers?" Maya is appalled that Momma speaks to the woman in this way. She already has low self esteem, a smart student in school who refuses to speak, who reads and gets good grades, but is too embarassed to participate because of her perceived low social status.
Momma left out the verb. Why not ask, How are you, Mrs. Flowers?With the unbalanced passion of the young, I hated her for showing her ignorance to Mrs. Flowers. It didn't occur to me for many years that they were as alike as sisters, separated only by formal education.
Mrs. Flowers has a little talk with Maya and tells her, essentially, that lack of education does not mean a person is stupid.
She said that I must always be intolerant of ignorance but understanding of illiteracy. That some people, unable to go to school, were more educated and even more intelligent than college professors. She encouraged me to listen carefully to what country people called mother wit. That is those homely sayings was couched the collective wisdom of generations.
Maya learns an important lesson. A woman that has reason to be "high and mighty" is not so. Instead, she explains that simple folk can be wise, and Maya understands that this is why her Momma can call Mrs. Flowers "Sister" - they are sisters in their humanity.
Grammar is a symbol, therefore, of something that separates people. In this case, education separates people, but something more important unites them - human dignity, respect for one another.