Question

Bahan ki beti ko kya kehte hain English meaning

Answer 1

The daughter of your sister will be your niece.

Niece is generally the daughter of one's brother, sister, brother-in-law or sister-in-law.

Whereas nephew is the son of one's brother, sister, brother-in-law or sister-in-law.

Conversely you are their uncle or aunt.

Actually niece and nephew can also be the daughter and son of any cousin.

Cousin is the son or daughter of any relative.

Hence, to answer your question behen ki beti that is daughter of your sister will be your niece.