Okay kiddo, so a PCI Mezzanine Card or PMC is kind of like a big sticker that you can put on your computer. It's a little piece of hardware that lets your computer do extra things or work better.
Think of your computer like your toy box. You can only play with the toys that you have in the box. But if you wanted to play with a new toy, you would need to go to the store and buy it first, right? Well, a PMC is like a new toy that you can buy for your computer.
A PMC can do all kinds of cool things. It can add extra memory to your computer, make it run faster, or help it talk to other devices. It can also give your computer new abilities, like being able to send and receive signals from satellites or other far-off things.
Like a sticker, a PMC card has to be put on in just the right way. First, you need to open up your computer (with the help of an adult, of course). Then, you have to find the right spot to put the PMC card. You have to make sure it clicks into place, just like when you're playing with a puzzle.
Once the PMC card is in place, you can turn your computer back on and start using it with your new toy! So, just like how you get to play with new toys and games, your computer can now play with new toys, too!