Yes, NATIONS is a Scrabble word!

Letter values in Scrabble US: N 1, A 1, T 1, I 1, O 1, N 1, S 1.

Is it a valid word?

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

a politically organized body of people under a single government
the people who live in a nation or country
United States prohibitionist who raided saloons and destroyed bottles of liquor with a hatchet (1846-1911)
a federation of tribes (especially Native American tribes)

Also: res publica, body politic, carry nation, carry amelia moore nation.