In everyday life a sacrifice costs you something, forgoing something you want or giving up something you have. In the Bible, a sacrifice also means a payment of something due God. Nearly all the sacrifices described in Leviticus involve slaying an animal.
In the New Testament, such blood sacrifices are done away, not because they went out of fashion but because they were fulfilled in the sacrifice of Jesus Christ on the cross.
All the sacrifices of the Old Testament could, at best, cover or bear away sin. The sacrifice of Jesus Christ on the cross, the shedding of His precious blood, did away with our sins forever.
Speaking of Jesus Christ, I John 2:2 says, “and He Himself is the propitiation for our sins; and not for ours only, but also for those of the whole world.” (It would be worth your while to look up in an online dictionary the meaning of the word, “propitiation.”)
So, that one great sacrifice of Christ has removed all obligation for us to offer any more sacrifices to God, right? Wrong.
“Through Him then, let us continually offer up a sacrifice of praise to God, that is, the fruit of lips that give thanks to His name. And do not neglect doing good and sharing, for with such sacrifices God is pleased.” (Hebrews 13:15f)