Yes, lefts is a Scrabble word!

Noun

1. Location near or direction toward the left side; i.e. the side to the north when a person or object faces east

2. Those who support varying degrees of social or political or economic change designed to promote the public welfare

3. The hand that is on the left side of the body

4. The piece of ground in the outfield on the catcher's left

5. A turn toward the side of the body that is on the north when the person is facing east