Jesus did the same with the cup after supper, saying, “This cup is the new covenant written in my blood, blood poured out for you.
Source: Luke 22:20 (The Message)
Jesus ushered in a new covenant (aka testament, agreement or contract). Jesus did it through the blood he shed for us on the cross. It completely blew out of the water the old covenant (aka testament, agreement or contract). This is a big deal and 2,000 years later we probably miss what this meant. The Jewish people and the disciples of Jesus knew what it meant.
Hebrews 8 gives us more insight into the new covenant. It is important to recognize that there were problems with the first covenant. How could God do that I wonder. Remember when Jesus said to them, “Because of your hardness of heart Moses permitted you to divorce your wives; but from the beginning it has not been this way.”
For if that first covenant had been faultless, there would have been no occasion sought for a second.
Here is more, indicating the transformation that was occurring at the time was making the old covenant obsolete.
When He said, “A new covenant,” He has made the first obsolete. But whatever is becoming obsolete and growing old is ready to disappear.
Not too much later, at the Council of Jerusalem (Acts 15), we learn that the new covenant opened up the way for non-Jews to participate as fully adopted children as followers of Jesus. It was agreed, with the guidance of the Holy Spirit, that nothing was required of the Gentile converts except faith in the Messiah; they were not bound by the Law of Moses. However, the council directed the Gentile Christians to abstain from certain things that were particularly offensive to their Jewish brethren – food sacrificed to idols, blood, meat of strangled animals and sexual immorality.
So Paul was confident to say to the non-Jews (Acts 13):
Therefore let it be known to you, brethren, that through Jesus forgiveness of sins is proclaimed to you, and through Jesus everyone who believes is freed from all things, from which you could not be freed through the Law of Moses.
The good news of the new covenant is that it ties together most of what we read in the New Testament (aka covenant). It is up to us to understand as much about this as we can as a framework for how to follow Jesus.