Yes, VESPERS is a Scrabble word!

Letter values in Scrabble US: V 4, E 1, S 1, P 3, E 1, R 1, S 1.

Is it a valid word?

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

the sixth of the seven canonical hours of the divine office; early evening; now often made a public service on Sundays
a planet (usually Venus) seen at sunset in the western sky
a late afternoon or evening worship service

Also: evening star.

Not playable in Scrabble US: HESPERUS.