The meaning of this sentence is that only by cultivating one's own character, correcting one's own thoughts and being able to manage one's family can one manage one's own country and finally make the world peaceful.
"If the ancient desire is obviously superior to the world, govern the country first; If you want to govern your country, you should first get your family together; If you want to reunite with your family, you should first repair your body; If you want to cultivate yourself, you should be upright first; If you want to be correct, be sincere first; To be sincere, you must know first, and you must know the style. If you know things, you will be honest, sincere, correct, repair, repair, rule the country, and rule the world. "
-The Book of Rites University