Yes, ARCHER is a Scrabble word!

Letter values in Scrabble US: A 1, R 1, C 3, H 4, E 1, R 1.

Is it a valid word?

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

a person who is expert in the use of a bow and arrow
(astrology) a person who is born while the sun is in Sagittarius
the ninth sign of the zodiac; the sun is in this sign from about November 22 to December 21

Also: sagittarius the archer.

Not playable in Scrabble US: SAGITTARIUS.