what did the girls discover in the furniture store that made Esperanza feel stupid?

The girls, Nenny and Esperanza, visit Gil's furniture store. It is actually a junk store run by an elderly African-American man. Gil points out a "pretty" music box to Nelly. Esperanza imagines "a pretty box with flowers painted on it, with a ballerina inside." The box turns out to be "just a wood box that's old".