What does Exodus 12:27 mean?

Tell them, This is the Passover sacrifice to the Lord, because he passed over the houses of the Israelites in Egypt and spared us when he struck down the Egyptians. Then the people bowed down and worshiped. Exodus 12:27 - Modern Text Bible

(The ritual is a way to tell the story of God’s rescue. The people respond with respect and gratitude.)