If you are my nth cousin then we have a common ancestor n+1 generations back. Your normal cousin is called a 1st cousin. Both you and your cousin are descended from the same grandparent(s).

If someone is your 10th cousin then 11 generations back both of you have the same 9th great-grandparent(s). 9th great-grandparents means great-great-great-great-great-great-great-great-great-grandparents.