Their job was to help Aaron’s descendants in the service of the Lord’s temple. They were to take care of the courtyards, the rooms, ceremonial purification of all holy items, and other jobs related to the service of God’s temple.
They appointed the priests by their divisions and the Levites by their divisions over the worship of God at Jerusalem, in accord with the book of Moses.
“Then the tent of meeting with the camp of the Levites will travel in the middle of the camps. They will travel in the same order as they camped, each in his own place under his standard.
At that time the Lord set apart the tribe of Levi to carry the ark of the Lord’s covenant, to stand before the Lord to serve him, and to formulate blessings in his name, as they do to this very day.