What is the significance of having many names in The House on Mango Street?Because I have read in so many chapterin which Esperanza talk about...

In The House on Mango Street,
Esperanza describes the given names and nicknames that she and others have. 
In describing her own name, Esperanza tells the audience that her name in Spanish means
"hope."  This is significant because Esperanza's name becomes a symbol for her
characterization--even though she will experience rough times living on Mango Street
(i.e. sexual harrassment, poverty, violence), she will still see hope in her life and
make plans to gain a brighter reality. 

This is true of
other characters as well.  For example, Geraldo No-Last-Name is a young man whom Marin
meets at a dance.  He is killed that night, but no one know who his family is or where
he has come from.  Geraldo's not having a last name represents his anonymity in this
country--he is an immigrant and has come to the U.S. to work to send money home to his
family.  But he is part of the mass of immigrants who have a similar experience, and no
one cares about them as individuals.  His not having a last name is symbolic of this
reality.