In the 500s AD, Benedict was the founder of a new Christian movement toward monasticism: living as monks or nuns. Already in the 300s, especially in Egypt, men and women had been going off by themselves into the desert, away from people, to live a life of prayer, devoted entirely to God. This followed earlier movements in India and China where Buddhist monks also retired from the world into caves cut into cliffs. People called these men and women monks (and the women gradually came to be called nuns).
But as there got to be more and more of these monks, all over Europe and Asia, and not just in the desert but even in towns and cities, it got harder and harder to figure out whether somebody was really devoting herself to God, or if she was really some kind of scam artist. In China, in the 400s AD the Wei emperor Dai Wudi closed many Buddhist monasteries and took their money.
Benedict wanted to prevent this sort of thing from happening to Christian monks by showing that they could regulate themselves. He organized a community of monks in Italy, and wrote up a set of rules for them to live by. Gradually people agreed, all over the Christian world, that you should only trust monks who lived by the rules of these communities. All monks should have somebody who was in charge of them and could vouch for their character.