Leviticus 3:8 And he shall lay his hand upon the head of his offering, and kill it before the tabernacle of the congregation: and Aaron’s sons shall sprinkle the blood thereof round about upon the altar.
When they offered their offering to the Lord they were to lay their hands on the offering before killing it. They were in essence acknowledging that this offering was their substitute. They deserved to die. They should have been offered but another would take their place. The sacrifice would be made. The blood would be sprinkled on the altar.
That is exactly what happens in Christ. He is our substitute. He takes our place. His blood goes to the altar for us. We are spared because another dies in our place!