'Burden' in the Bible

Do this to them and they will live and not die when they come near the most holy things. Aaron and his sons will go and appoint them, each one to his task and burden.

According to {the command} of Yahweh by the hand of Moses {they were mustered}, each man according to his service and according to their service and according to their burden; and so they were counted by him just as Yahweh commanded Moses.