The Human Rights Act is a set of rules created in 1998 to make sure everyone in the United Kingdom is treated equally and fairly. It's like a big instruction book that tells people what they can and can't do to others.
For example, it says that everyone has the right to life, the right not to be treated in a cruel or inhuman way, and the right to a fair trial. It means that no one can hurt you, and you will be able to have your say in court if you are accused of something.
It's a bit like when you are playing with your friends, and you all agree on the rules of the game before you start. The Human Rights Act is like that, but for grown-ups, so everyone knows what they can and can't do. It's important because it means that everyone gets treated the same, no matter what they look like or where they come from.