The Children of Israel were in slavery to Pharaoh, who is a picture in the Bible of Satan. God commanded the Children of Israel to kill an adult male lamb, without any blemish. This is a Biblical picture of Jesus Christ. The lamb had to be slaughtered, and its blood placed on the wooden door posts, a Biblical picture of the Cross. None of its bones should be broken.
This foreshadowed the Crucifixion when the Angel of Death passed over their house. Nobody in the house would die if the blood of the lamb was placed on the door posts. This is a picture of the Crucifixion. Nobody would suffer the wrath of God if they identified with the Blood of Jesus Christ, spilled at the Crucifixion, the Atonement by Jesus Christ for sin.