Where does “sala” come from?

sala (Old Dutch) comes from Proto-West Germanic sāli, from Proto-Germanic saliz, from Proto-Indo-European sol- — whole.

Ancestry of “sala”, step by step

Step	Language	Word	Meaning
1	Proto-West Germanic	sāli	happiness, prosperity; proper, appropriate time
2	Proto-Germanic	saliz	house; dwelling; hall; room
3	Proto-Indo-European	sol-	whole

sala — Etymology, Origin & Word History | Etymology Explorer