Four skinny trees stand outside Esperanza and Nenny's bedroom. Esperanza says that they are the only things that understand her, and she is the only one that understands them. Nenny definitely doesn't understand while Esperanza communes with the trees from the window, Nenny just sleeps.
The trees are kind of like Esperanza – they're skinny with pointy elbows. They don't belong here, but they're here. They have a secret strength.
There are four trees, and when one sags, they all droop with their arms around one another. Does this sound like anyone we know? What about Esperanza and her three close friends?
The trees teach, Esperanza says. They say: "Keep, keep, keep" (29.3).
Whenever Esperanza feels discouraged, she looks at the four trees, "who grew despite concrete" (29.4).