What does Leviticus 20:17 mean?

If a man sleeps with his sister—whether she’s his father’s daughter or his mother’s daughter—and they see each other naked, that’s shameful. They’ll be cut off from their people. He’s exposed his sister, and he’ll have to bear the consequences. Leviticus 20:17 - Modern Text Bible

(This law forbids sexual relations between siblings, emphasizing the shame and social consequences, not just the act itself.)