Yes, ALLIES is a Scrabble word!

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

Is it a valid word?

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

the alliance of nations that fought the Axis in World War II and which (with subsequent additions) signed the charter of the United Nations in 1945
in World War I the alliance of Great Britain and France and Russia and all the other nations that became allied with them in opposing the Central Powers
an alliance of nations joining together to fight a common enemy
a friendly nation
an associate who provides cooperation or assistance