Yes, AREAS is a Scrabble word!

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

Is it a valid word?

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

a particular geographical region of indefinite boundary (usually serving some special purpose or distinguished by its people or culture or geography)
a subject of study
a part of an animal that has a special function or is supplied by a given artery or nerve
a particular environment or walk of life
a part of a structure having some specific characteristic or function
the extent of a 2-dimensional surface enclosed within a boundary

Also: surface area.