What does the author mean when she says Victor is angry “with a white man’s anger, too big for him” in the novel, July’s People?

The author means Victor, just a boy, is being accused of stealing what he thinks of as garbage from a black man. He is humiliated by the accusation and resentful that a black man is saying negative things about him. He doesn’t understand shame and humiliation, but these emotions, for him, are merely wrapped into an anger that he doesn’t rightfully understand.