What does Leviticus 10:6 mean?

Moses told Aaron and his other sons, Eleazar and Ithamar, 'Don't let your hair hang loose or tear your clothes in mourning, or you'll die too and bring God's anger on everyone. The rest of the Israelites can mourn, but you must not leave the entrance to the tent, or you'll die, because the Lord's anointing oil is on you.' So they did what Moses said. Leviticus 10:6 - Modern Text Bible

(Aaron and his remaining sons are told not to mourn in the usual way, because they're still serving as priests. Their special role means they have to follow different rules, even in grief.)