Okay kiddo, have you ever seen a phone book? It's a big book filled with all the phone numbers in your town. A long time ago, people would use big machines called "terminals" to look up phone numbers and make phone calls.
Terminals were like computers, but much simpler. They had a screen and a keyboard, but they were not as fancy as the computers we use today. People would type in a phone number on the keyboard, and the terminal would connect them to the phone network so they could talk to the person on the other end.
Nowadays, we don't really use terminals to make phone calls anymore. But sometimes, people still use terminals to communicate with other computers. For example, if a programmer wants to connect to a server, they might use a terminal to type in commands and access files on that server.
So even though we don't really use terminals for making phone calls anymore, they're still important for connecting us to other machines and networks.