bhagina
Your sister's daughter is your niece, her granddaughter is your "great niece"... or you could just call her by name.
you call her your daughter's husband's sister
Your daughter is your sister's niece. Your daughter's son is her great nephew.
You would call your sister's daughter your niece.
Niece
Your sister's daughter is your niece.
Your sister's daughter, to you, is your neice. (You are her aunt or uncle). If the daughter were actually a son, he would be you nephew.
She is your niece
Your niece
You brother's daughter is your niece, just as your sister's daughter is your niece. The English language does not have different terms for daughter of brother and sister.
Your niece.