"We Real Cool," by Gwendolyn Brooks, is about seven teenage boys who have left school to spend their time playing pool.
The boys brag that they "lurk late," "sing sin" and "thin gin."
They also celebrate that they "Jazz June." This phrase has become controversial, but Brooks herself has explained that she chose the month of June as a symbol of "the establishment," the accepted way of doing things. By saying that they "jazz June," the boys are saying that just like jazz musicians take liberties with standard melodies, they take liberties with the standard, conventional way of doing things.
The poet, however, does not seem to approve of the boys' abandonment of education. She ends her poem with the sentence, "We / Die soon." The poet is saying that the boys' "freedom" from education and healthy living will not have a happy ending.