Command and control malware is like a secret message between two friends. Imagine you and your friend have a secret code you made up to communicate when you're apart. This secret code is like how a virus communicates with its creators.
Except, in this case, one friend is someone you don't know, and they are sending you messages on your computer secretly. This is bad because they have evil plans, and they want your computer to be their friend.
These bad guys send you secret messages that tell your computer what to do, like copying all of your pictures and sending them back to them or joining in on an attack on other people's computers. This message is called a command, and your computer will do exactly what the bad guys tell it to do.
This is why it's called "command and control" malware.
To protect your computer, you should always use antivirus programs and avoid clicking on suspicious links or downloading strange files. It's important to keep yourself safe from these bad guys who want to control your computer without your permission.