Meaning: When there is harmony, peace and order become stronger, while chaos and confusion become weaker.
Choice of Words: Harmony is a state of peace and agreement among people or things. Reigns means to have power or authority over a place or group of people. Chaos is a state of complete disorder and confusion. Retreats means to move back or withdraw from a place or situation. When you put them together, the sentence suggests that order and peace are becoming stronger, while disorder and confusion are fading away.