Yes, HOLDER is a Scrabble word!

Letter values in Scrabble US: H 4, O 1, L 1, D 2, E 1, R 1.

Is it a valid word?

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

a holding device
a person who holds something
the person who is in possession of a check or note or bond or document of title that is endorsed to him or to whoever holds it