Yes, THEATRES is a Scrabble word!

Letter values in Scrabble US: T 1, H 4, E 1, A 1, T 1, R 1, E 1, S 1.

Is it a valid word?

THEATRES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a building where theatrical performances or motion-picture shows can be presented
the art of writing and producing plays
a region in which active military operations are in progress

Also: dramatic art, field of operations, theater of operations, theatre of operations.