Imagine you are having a party in your room with your friends, and you want everyone to come and have fun. But at some point, too many people come into the room, and it starts to get crowded. You try to add more chairs and tables to accommodate everyone, but eventually, there are just too many people to fit in the room comfortably.
This is similar to what happens when a group of people reaches a critical mass, which means there are so many people that they start to face some problems. In the case of a party, it's limited space, but in other situations, it can be different things.
For example, let's say there is a town with a small lake nearby. A few people like to go swimming in the lake, but as more and more people start showing up to swim, the lake starts to become overcrowded. Suddenly, people start bumping into each other, and there's just not enough space for everyone to swim around comfortably.
Now imagine two groups of people have different ideas about how to deal with this situation. The first group thinks that there should be some rules to ensure that the lake doesn't get too crowded. They suggest that people should only be allowed to swim there at specific times of the day or that there should be a limit to the number of people who can visit the lake.
The second group thinks that everyone should be able to swim whenever they want to, and that rules would only make things worse. They argue that everyone should simply try to make the best of the situation.
This is a conflict, where there are different ways to deal with the problem of critical mass. Both groups state valid points, but it's up to the town council or whoever is responsible for making such decisions to analyze and solve the issue.