This is a polite way of speaking of sexual relations. You may have to use other words in your translation. Alternate translation: "a man has sexual relations with his aunt" (See: [[rc://en/ta/man/jit/figs-euphemism]])
Here the idiom “uncovers … nakedness” means “disgraces.” See how you translated this idiom in [Leviticus 18:7](../18/07.md). Alternate translation: “he has disgraced his uncle” or “he has shamed his uncle” (See: [[rc://en/ta/man/jit/figs-idiom]])