A hyperbole is an exaggeration and is used for emphasis. In The House on Mango Street, the following passage contains a hyperbole:
On Tuesdays, Rafaela's husband comes home late because that's the night he plays dominoes. And then, Rafaela, who is still young but getting old from leaning out the window so much, gets locked indoors because her husband is afraid Rafaela will run away since she is too beautiful to look at (from the chapter Rafaela Who Drinks Coconut and Papaya Juice on Tuesdays).
The passage states that Rafaela is rapidly growing "old from leaning out the window so much." This hyperbole emphasizes Rafaela's dreary existence. She has nothing to look forward to in life, apart from watching and waiting for her husband's return.
Rafaela's husband leaves her at home when he goes to the bar to enjoy himself and to cavort with other women. Rafaela knows that there is music at the bar, but she is not allowed to go; she can only hope to have an opportunity to dance there one day before she becomes too old to do so. The hyperbole also emphasizes Rafaela's powerlessness.
Another example of hyperbole comes from the chapter Darius and the Clouds.
You can never have too much sky. You can fall asleep and wake up drunk on sky, and sky can keep you safe when you are sad. Here there is too much sadness and not enough sky. Butterflies too are few and so are flowers and most things that are beautiful. Still, we take what we can get and make the best of it.
Of course, the sky cannot keep us safe and we cannot get "drunk" on the sky. The author uses hyperbole to draw our attention to small blessings: even when there is a dearth of beautiful things around us, we still have the sky. It belongs to all of us and is always there. Its wide expanse symbolizes freedom and hope.