There is a verb in that noun! A peacemaker makes peace! That means we have to do and say something that yields peace.
Many Christians today believe that because God loves them and they are saved by grace and not by works, that they do not need to do anything else. They believe once saved always saved and I can go about my life however I want. We definitely have been saved by grace through faith (Ephesians 2:8-9) and we could never have saved ourselves by works. But, now we are to walk in our new relationship and position in Yeshua Christ. He has set us free, but now we need to turn and walk by the Holy Spirit instead of by the old flesh. This encouragement and exhortation is in all the gospel letters!
Galatians 5 is a one good example. “For you, brethren, were called for freedom; only use not your freedom for an occasion to the flesh, but through love be servants one to another. (Galatians 5:13). It continues to tell us to walk in the Spirit and the fruits of the Spirit (including peace) and not the desires of the flesh. We need to DO and MAKE peace as ambassadors and sons/daughters of the Peacemaker.
“Blessed are the peacemakers for they will be called the sons of God.” Matthew 5:9.