Yes, GLABELLA is a Scrabble word!

Letter values in Scrabble US: G 2, L 1, A 1, B 3, E 1, L 1, L 1, A 1.

Is it a valid word?

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

a smooth prominence of the frontal bone between and above the eyebrows; the most forward projecting point of the forehead in the midline at the level of the supraorbital ridges

Not playable in Scrabble US: MESOPHYRON.