I just say.. YO MAMA, but she is your niece.
Are you asking what you call your brothers daughter? Well if you are your brothers daughter is called your niece.
Niece
A niece
A niece
A cousin.
natini
Your niece.
Your nephew?
Its would be your neice
Niece
The daughter of your brother is your niece.
Your father's brother's son is your first cousin and your daughter's second cousin.