Yes, PROXIES is a Scrabble word!

Letter values in Scrabble US: P 3, R 1, O 1, X 8, I 1, E 1, S 1.

Is it a valid word?

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

a person authorized to act for another
a power of attorney document given by shareholders of a corporation authorizing a specific vote on their behalf at a corporate meeting