Yes, REALIZATION is a Scrabble word!

Letter values in Scrabble US: R 1, E 1, A 1, L 1, I 1, Z 10, A 1, T 1, I 1, O 1, N 1.

Is it a valid word?

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

coming to understand something clearly and distinctly
making real or giving the appearance of reality
a musical composition that has been completed or enriched by someone other than the composer
a sale in order to obtain money (as a sale of stock or a sale of the estate of a bankrupt person) or the money so obtained
the completion or enrichment of a piece of music left sparsely notated by a composer
something that is made real or concrete

Not playable in Scrabble US: REALISATION, ACTUALISATION.