In literature, exposition is the part of a story in which the author sets the stage for what will happen. It is where the theme, characters, conflicts, setting and/or circumstances are laid out. It is during the exposition that we get to know some fundamental facts about the characters that will help us understand who they are and keep up with their development through the story.
In "Now, facts are facts. Wiley was a boy. He and his mama lived by themselves with just Wiley’s dogs," we have an exposition because the character Wiley is being introduced to us. We now know he is a boy who lives with his mother and dogs. Those are simple facts about Wiley that set the stage for bigger conflicts and happenings. We need to know a bit about the characters to feel connected to them.
