Section 230 of the Communications Decency Act is a law that says that internet platforms like websites and social media sites are not responsible for things that people post on their platforms.
Think of it like a playground. The teachers are like the people who run the website, and the kids playing are like the people who use the website. If one kid writes something mean on the wall, the teacher can't get in trouble for it. They didn't write it, and they didn't tell the kid to write it.
This law is important because it means that people can't sue the website for something that someone else wrote. It also means that websites can allow people to post whatever they want without getting in trouble for it. However, there are still some things that are not allowed, like illegal content such as hate speech or posts promoting violence.
So just like a playground, internet platforms have some rules. But as long as they stick to those rules, they can let people use the site in whatever way they want without getting in trouble for it.