'Duties' in the Bible

They may assist their colleagues in the tent of meeting, to attend to needs, but they must do no work. This is the way you must establish the Levites regarding their duties."

I myself have chosen your brothers the Levites from among the Israelites. They are given to you as a gift from the Lord, to perform the duties of the tent of meeting.

But you and your sons with you are responsible for your priestly duties, for everything at the altar and within the curtain. And you must serve. I give you the priesthood as a gift for service; but the unauthorized person who approaches must be put to death."