Alright kiddo, have you ever seen those video games or cartoons that have very simple and blocky looking characters and objects? That's called "low poly".
It's kind of like taking a picture of something and instead of having lots of tiny details and curves, you just draw it as simplified shapes.
Low poly art is often used in video games because it's easier for the game to run quickly and smoothly when the characters and objects are simple. Plus, it can look really cool and give a unique style to the game or animation.
So, low poly just means things that are made with fewer details and simpler shapes. It's like drawing a picture with big, bold lines instead of lots of tiny little ones.