UEFI stands for "Unified Extensible Firmware Interface". It's a fancy name for a special software that helps your computer start up when you turn it on.
Think of UEFI like a traffic director. When you turn on your computer, UEFI checks to make sure everything is working properly. It talks to all the different parts of your computer, like the hard drive, keyboard, and mouse, and makes sure they're all working together.
Once UEFI has made sure everything is working, it hands control over to the operating system, which is like the captain of the ship that takes you where you want to go on your computer.
In the past, computers used something called BIOS (Basic Input/Output System) to start up. UEFI is like a newer, fancier version of BIOS that can do more things and work with newer technologies.
Overall, UEFI may not be something you think about often, but it's an important part of your computer that helps it work properly and get you where you want to go.