Okay buddy, let me break it down for you. A DirectX plugin is like a special tool that helps your computer show you really cool and fancy graphics when you're playing games or watching videos.
It's kind of like having a magic wand that works with your computer's graphics engine to create super cool effects. But instead of waving a wand to make things happen, you just download and install the plugin, and it does the work for you.
Think of it like a toy box with lots of cool toys. The DirectX plugin is like a new toy that you didn't have before. When you add it to your toy box (aka your computer), you suddenly have a really cool new toy to play with. And that toy helps create all kinds of fun things for you to explore and enjoy.
So, in short, DirectX plugins are super cool and help make your computer graphics look even more amazing!