It means everything in its place, in harmony, whole. Let not your hearts be troubled, neither let them be afraid. Wherever Jesus, with His words and His wounds, is there is peace aplenty. Sin is atoned for. Death is conquered.
Life comes brimming over.
Jesus, the Crucified and Risen One, is your peace. See His wounds, the marks of His death - the death He endured in order to save you. Rejoice in those wounds. Recall the water and the blood that flowed from His sword pierced side. They are His sacraments of peace and life and salvation poured out for you.