Where does “ירושלים” come from?

ירושלים (Yiddish) comes from Hebrew יְרוּשָׁלַיִם — Jerusalem.

Ancestry of “ירושלים”, step by step

Step	Language	Word	Meaning
1	Hebrew	יְרוּשָׁלַיִם	Jerusalem

ירושלים — Etymology, Origin & Word History | Etymology Explorer