Yes, SPA is a Scrabble word!

Letter values in Scrabble US: S 1, P 3, A 1.

Is it a valid word?

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

a health resort near a spring or at the seaside
a fashionable hotel usually in a resort area
a place of business with equipment and facilities for exercising and improving physical fitness

Also: watering place, watering hole, resort hotel, health spa, health club.