An endowment is a gift. It might be money given to an institution like a college. Or, an endowment might be a natural gift, say of a physical attribute or a talent. If you lack the endowment of musical talent, you could play the tambourine.
To endow means "to give or bequeath," and the background of the word endowment goes back to the 15th Century, where it was used to refer to money or property that is given to an institution. An example can be found in the National Endowment for the Arts, an organization dedicated to providing grants to fund artistic endeavors. Your natural endowments — speed, agility, endurance — make you an excellent soccer player. If only you could wake up in time for practice.