Yes, LOCALIZATION is a Scrabble word!

Letter values in Scrabble US: L 1, O 1, C 3, A 1, L 1, I 1, Z 10, A 1, T 1, I 1, O 1, N 1.

Is it a valid word?

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

a determination of the place where something is
(physiology) the principle that specific functions have relatively circumscribed locations in some particular part or organ of the body

Also: localization of function, localisation of function, localization principle, localisation principle.

Not playable in Scrabble US: LOCALISATION.