Yes, BRASSES is a Scrabble word!

Letter values in Scrabble US: B 3, R 1, A 1, S 1, S 1, E 1, S 1.

Is it a valid word?

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

an alloy of copper and zinc
a wind instrument that consists of a brass tube (usually of variable length) that is blown by means of a cup-shaped or funnel-shaped mouthpiece
the persons (or committees or departments etc.) who make up a body for the purpose of administering something
impudent aggressiveness
an ornament or utensil made of brass
the section of a band or orchestra that plays brass instruments
a memorial made of brass

Also: brass instrument, governing body, brass section, memorial tablet.