en_tn_condensed/lev/13/03.md

skin of his body

Here "his" refers to the person with the skin disease.

leprosy

Leprosy was a skin disease. There were different skin diseases called leprosy in the Bible.

he must pronounce him unclean

"the priest must pronounce the man unclean." The man whom other people must not touch is spoken of as if he were physically unclean.