What does Judges 19:24 mean?

'Look, here's my daughter, who's never been with a man, and his concubine. I'll bring them out to you. Abuse them if you must, but don't do this horrible thing to my guest.' Judges 19:24 - Modern Text Bible

(In desperation, the old man offers his own daughter and the Levite's concubine to the mob, trying to protect his guest at a terrible cost.)