Yes, FES is a Scrabble word!

Letter values in Scrabble US: F 4, E 1, S 1.

Is it a valid word?

FES is a valid word in the official Scrabble dictionary (US) and the UK Scrabble Dictionary, but not in Words with Friends (ENABLE).

a city in north central Morocco; religious center
a heavy ductile magnetic metallic element; is silver-white in pure form but readily rusts; used in construction and tools and armament; plays a role in the transport of oxygen by the blood

Also: atomic number 26.