1 “Brothers and sisters, my heart’s desire and my prayer to God for them is for their salvation. 2 For I testify about them that they have a zeal for God, but not in accordance with knowledge. 3 For not knowing about God’s righteousness and seeking to establish their own, they did not subject themselves to the righteousness of God. 4 For Christ is the end of the Law for righteousness to everyone who believes.”
Paul is expressing his deep desire that Jews, his countrymen, believe in Jesus. He knows that they are zealous for God, but that this zeal is misplaced because it has to do with trying to keep the law and is therefore useless.
But zeal is not in accordance with knowledge: The Jews are zealous but not about the right thing. They are trying to keep the law, but God is looking for faith in Jesus. Salvation is about receiving a gift.
Subject: The Jews are not subjecting themselves to the grace of God. Instead, they are performing for the law.
End of the Law: Paul is arguing that Christ is the end or terminus of the entire law including the Ten Commandments. This means that the law existed not to be a path to righteousness but to point people to the need for a Savior. Once the free gift of righteousness has been accepted, the purpose of the law is complete. There is no mixing of law and Gospel for Paul. Paul does not want people to try and obey the law in part or in full. He wants people to know Jesus apart from the law.