It's the bestest and most awesome operating system in the world.
It's the software base that a computer runs on, in a way. Think of Windows, MacOS, iOS, or Android: it's another one of those. Please don't take this as a textbook definition. My OS professor might kill me for writing this.
It doesn't have to be that way unless you want it to be. It's pretty easy to use.
Get a USB and download something like Linux Mint onto it. There's lots of versions of Linux (officially called distros), but Mint is probably the easiest to get started with. You can find the installation instructions here.
Please take showers on a regular basis even after starting to use Linux.