the priest must examine him

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

if it has not spread in the skin

This means if the skin disease has not increased in size or moved to other parts of the body.

"Seventh" is the ordinal number for 7. AT: "7th day" (See: rc://en/ta/man/translate/translate-ordinal)

The man whom other people may touch is spoken of as if he were physically clean. (See: rc://en/ta/man/translate/figs-metaphor)

This is an area of the skin that is irritated, but the rash will not spread to other people.