Yes, FLARES is a Scrabble word!

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

Is it a valid word?

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

a shape that spreads outward
a sudden burst of flame
a burst of light used to communicate or illuminate
reddening of the skin spreading outward from a focus of infection or irritation
a sudden recurrence or worsening of symptoms
a sudden eruption of intense high-energy radiation from the sun's surface; associated with sunspots and radio interference
am unwanted reflection in an optical system (or the fogging of an image that is caused by such a reflection)
a sudden outburst of emotion
a device that produces a bright light for warning or illumination or identification
a short forward pass to a back who is running toward the sidelines
(baseball) a fly ball hit a short distance into the outfield

Also: solar flare, flare pass, flame up, blaze up, burn up, flare out, flare up, break open, burst out.