Cities of refuge were special cities that were set up in ancient times to help protect people who had accidentally killed someone from being killed themselves. In those days, if someone killed another person (even accidentally), the family of the person who was killed would often seek revenge and try to kill the person who did it. This could lead to a cycle of violence where more and more people would be hurt or killed.
So, to help prevent this from happening, the leaders of the time decided to set up these cities of refuge. There were six of these cities throughout the land, and they were strategically placed so that they were accessible to anyone who needed them. If someone accidentally killed someone else, they could flee to one of these cities and be safe. Once they arrived, they were protected from anyone seeking revenge, and they could stay there for as long as they needed to.
But it wasn't just a place to hide. The cities of refuge also served as a place where the accused could be heard in front of a fair trial. This means that they would have a chance to explain what happened, and if it was really an accident, they could be acquitted (or found not guilty).
Overall, the cities of refuge were an important part of ancient society. They helped prevent unnecessary violence, protected innocent people, and ensured that everyone had a fair chance to be heard in front of a trial.