Yes, SYMBOLISM is a Scrabble word!

Letter values in Scrabble US: S 1, Y 4, M 3, B 3, O 1, L 1, I 1, S 1, M 3.

Is it a valid word?

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

a system of symbols and symbolic representations
the practice of investing things with symbolic meaning
an artistic movement in the late 19th century that tried to express abstract or mystical ideas through the symbolic use of images

Not playable in Scrabble US: SYMBOLISATION.