Yes, FLUIDS is a Scrabble word!

Letter values in Scrabble US: F 4, L 1, U 1, I 1, D 2, S 1.

Is it a valid word?

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

a substance that is fluid at room temperature and pressure
continuous amorphous matter that tends to flow and to conform to the outline of its container: a liquid or a gas