Okay, so let's imagine that names are like labels that we put on people to show who they are. Just like we have different labels for different things.
Now, a surname is a special kind of name that usually belongs to a family. It helps us know which family a person belongs to. For example, if your dad's name is John Smith, your surname would also be Smith because you are part of the same family.
Now, there are many different surnames in the world, and one of them is Chad. Chad can be a surname, meaning that there are some families who have this as their last name. Just like how some families have the last name Smith or Johnson, some families have the last name Chad.
So, if someone's last name is Chad, it means that they belong to a family with that name. It's just a way to help people know which family they are a part of. And it's important because family is a big part of who we are and where we come from!