For he himself is our peace, who has made the two one and has destroyed the barrier, the dividing wall of hostility, by abolishing in his flesh the law with its commandments and regulations. His purpose was to create in himself one new man out of the two, thus making peace…
The context of this passage in Ephesians 2 is a contrast between Jews and Gentiles. The Jews attained their salvation by following the laws of God, sacrifices, and circumcision. The Gentiles had no such path to God because they did not know Him at all.
With Jesus, the barrier was removed so that the Gentiles could be saved as well. They could not follow the law because they did not have the law. So Jesus abolished the law, making salvation attainable for Jews and Gentiles alike.
Jesus did not make the law worthless or null and void. There is still value in following the law today. What He did was make it that salvation was not gained through following the law.
Because the Gentiles can be saved through Jesus just as the Jews, there is unity in Christ. This is the peace that Paul writes about in Ephesians 2.