The shadow of the Old Testament (Tanakh) sacrifices point to the New Testament. The entire Passover service is intensely and highly symbolic of just that. Luke 22 describes the last supper (Passover) and Matthew 26-27 describes every detail of Good Friday.
In the Old Testament (Tanakh), there are many specific blood sacrifices listed and each one was a covering over the particular sin or sins, an atonement. This is why the sacrifices had to be repeated, and this is why there is the annual Jewish holiday, Yom Kippur, the day of Atonement.
In the New Testament, at the very central heart of the gospel is that the saving death of Jesus is the final atonement, for it is the propitiation: the quenching of God’s wrath for us when He completely removed our sins and took them onto Himself (expiation) thereby reconciling those who believe to God forever! Our sin (ALL of our sin, our entire body of sin; past, present, future) was imputed onto Jesus, and the righteousness of Jesus was imputed onto us, therefore called double imputation. (Romans 3:21-26, 1 John 2:2)
Good Friday (In 2021: Friday April 2) is the recognition of just what happened in His death. (Although it does not end there. It is Friday, but Sunday is coming; Resurrection Sunday (Easter)!