Yes, GOALIES is a Scrabble word!

Letter values in Scrabble US: G 2, O 1, A 1, L 1, I 1, E 1, S 1.

Is it a valid word?

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

the soccer or hockey player assigned to protect the goal
the defensive position on an ice hockey or soccer or lacrosse team who stands in front of the goal and tries to prevent opposing players from scoring

Not playable in Scrabble US: NETKEEPER.