What does Leviticus 21:23 mean?

He just can't go behind the curtain or approach the altar, because of his condition. He must not disrespect the holy places, since I am the Lord who sets them apart as holy. Leviticus 21:23 - Modern Text Bible

(The restriction is about maintaining the special status of the sanctuary. The priest isn't shamed or cast out, but he can't perform the most sacred rituals.)