Where does “sala” come from?

sala (Bikol Central) comes from Spanish sala, from Basque zahar, from Proto-Basque *za(h)ar — old.

Ancestry of “sala”, step by step

Step	Language	Word	Meaning
1	Spanish	sala	room; large hall; ward
2	Basque	zahar	old, aged
3	Proto-Basque	*za(h)ar	old