In the United States, civil liberties are the things that people are allowed to do and say without the government stopping them. It's like when your parents tell you that you can play with your toys as long as you're not hurting anyone else. That's how civil liberties work too.
Some of these civil liberties are written down in the Bill of Rights, which is like a list of rules that the government has to follow. For example, the first amendment says that people can say whatever they want without the government punishing them, as long as it's not going to hurt anyone else.
Other civil liberties include the right to practice any religion you want, the right to be secure in your house and belongings, and the right to a fair trial if you're accused of a crime.
These civil liberties are very important because they help to protect people's freedoms and rights. The government can't just do whatever they want and take away these liberties because they are written into the laws of the land.