Answer:
The sentence uses a hyperbole to describe the mess in the kid's room. It is also a metaphor, because it uses literal language to describe the subject. A hyperbole is an extreme exaggeration, used to emphasize a description of something. In the sentence, the hyperbole is "...a disaster area." The room is not actually a scene of a disaster, but the phrase is used to show that there is a large mess.
Good luck ^^