In previous verses and chapters we see that God not only saved us from the penalty of sin but also the power of sin.
Power of sin is broken over our lives.
Romans 6:14 ESV
14For sin will have no dominion over you, since you are not under law but under grace.
The Law has the power to point out sin but doesn’t have the power to remove it.
It has the ability to let us know what sin is and areas in our life that we need to deal with but does not give us the power to overcome those areas.
It shows us were we fall short of the Glory of God.
Now as in Paul’s day there are people who would bring up well if there is no law (not talking about civil law here) all’s we would have is lawless people. You have to be under the law for it gives us guidelines, the law gives us rules, the law gives us safety. Its ridicules to say we are not under the law.
Most of us understand Law for example the 10 commandments, but not many of us understand grace.