This is a polite way of saying that the daughters had not had sexual relations with any man. You may need to use another euphemism in your language. See how you translated similar words in [Genesis 4:1](../04/01.md). (See: [[rc://en/ta/man/jit/figs-euphemism]])
The two men were guests in Lot's home, so he needed to protect them. The word "roof" is a synecdoche for the whole house and a metaphor for Lot protecting them. Alternate translation: "into my house, and God expects me to protect them" (See: [[rc://en/ta/man/jit/figs-synecdoche]] and [[rc://en/ta/man/jit/figs-metaphor]])