Your daughter's daughter is your granddaughter, and you would be her grandmother or grandfather.
Cousins
She is your first cousin.
2nd cousin
Your daughter is your brother's niece. Your brother is your daughter's uncle
Your nephew and your daughter are first cousins.
Incest
my great grand-daughter
You are cousins
she would be my cousin
You are First Cousins
Your daughter and your niece are first cousins to each other.
daughter