What relation is she to me?

Your dad and his brother are siblings.

The children of each are first cousins

You and this girl are first cousins

The brother is your uncle; since he has died, your late uncle. All of his children are your first cousins. When you and she are old enough, find that special someone and have children of your own,

You will be first cousin once removed to hers, and she to yours;

They will be second cousins to each other.

First cousin, daughter of your uncle!

She is your first cousin

He is your first cousin whether your father is alive or deceased.

1st cousin

first cousin