Mrs. Johnson is depicted as the Younger family's nosy, jealous neighbor who briefly visits their apartment to see how Lena and the family are handling their recent fortune. When Mrs. Johnson stops by, Lena and the others are unenthusiastic about her presence but do their best to remain polite. Mrs. Johnson happily accepts a piece of sweet potato pie and tells Lena,

Oh honey, I can’t stay hardly a minute—I just dropped in to see if there was anything I could do (Hansberry, 101).

The audience realizes that Mrs. Johnson has no intention of helping the Youngers with anything and goes out of her way to discuss how black families are being attacked for moving into white neighborhoods. Her comments are particularly unsettling given the fact that she is aware of Lena's purchase in Clybourne Park. The audience can easily tell that Mrs. Johnson resents the Younger family's fortune, and Hansberry uses her character to illustrate how jealous community members present another obstacle that the Youngers must overcome.

Part of the reason behind Mrs. Johnson's visit to the Youngers is out of plain nosiness and a sense of intrusion.  She is jealous of the aspirations of the Younger family and displays a certain sense of resentment towards them.  She raises the fears of the Youngers in telling them about the hate crimes that have been committed in Clybourne Park, the neighborhood to which the Youngers are moving.  Her presence in the play is meant to display another set of obstacles that the Youngers face.  Indeed, they are beset by the challenges of race and class.  Through Mrs. Johnson, they are also challenged by some of the members of their community, who privately covet the opportunity for success that is presented to the Youngers.