What does Leviticus 10:9 mean?

Moses said to Aaron, and to Eleazar and to Ithamar, his sons, “Don’t let the hair of your heads go loose, and don’t tear your clothes; so that you don’t die, and so that he not be angry with all the congregation; but let your brothers, the whole house of Israel, bewail the burning which Yahweh has kindled.

You shall not go out from the door of the Tent of Meeting, lest you die; for the anointing oil of Yahweh is on you.” They did according to the word of Moses.

Then Yahweh said to Aaron,

You are to make a distinction between the holy and the common, and between the unclean and the clean.

You are to teach the children of Israel all the statutes which Yahweh has spoken to them by Moses.”

Moses spoke to Aaron, and to Eleazar and to Ithamar, his sons who were left, “Take the meal offering that remains of the offerings of Yahweh made by fire, and eat it without yeast beside the altar; for it is most holy;