Yes, ABACA is a Scrabble word!

Letter values in Scrabble US: A 1, B 3, A 1, C 3, A 1.

Is it a valid word?

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

a kind of hemp obtained from the abaca plant in the Philippines
Philippine banana tree having leafstalks that yield Manila hemp used for rope and paper etc

Also: manila hemp, manilla hemp, musa textilis.