Yes, BREATHER is a Scrabble word!

Letter values in Scrabble US: B 3, R 1, E 1, A 1, T 1, H 4, E 1, R 1.

Is it a valid word?

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

a short respite
air passage provided by a retractable device containing intake and exhaust pipes; permits a submarine to stay submerged for extended periods of time

Also: breathing place, breathing space, breathing spell, breathing time, snorkel breather.

Not playable in Scrabble US: SCHNORCHEL.