The purpose of exposition is to inform the readers about the plot, character, setting, and theme of the story.
Cuarón tells his entire story with a minimum of explanation or exposition. He allows the pictures to explain themselves.
“I cannot stand explanation in movies,” Cuarón says during a recent visit to San Francisco. “I cannot stand exposition. I prefer participation. You set up a situation and audiences have to make their own conclusions. I was not interested in explaining infertility, because if you start explaining, it becomes about that.”
What Cuaron dislikes is the “information dump,” “exposition dump,” or “plot dump.” Information dumps expressed by characters in dialogue or monologue are sometimes referred to as “idiot lectures.”
This was made fun of in the Austin Powers film series which has a character named Basil Exposition whose job was to repeatedly plot dump as a parody of the process in movies with serious plots.