What does Leviticus 16:4 mean?

He has to put on a sacred linen tunic, linen underwear, tie a linen sash around his waist, and wear a linen turban. These are sacred clothes, and he has to bathe before putting them on. Leviticus 16:4 - Modern Text Bible

(Aaron must wear special clothes and wash himself, showing respect and purity before entering the holy place.)