Mimesis means copying or imitating. It's like when you see something or someone doing something, and you try to do it the same way. For example, if you see your best friend jumping, you might try to jump the same way they did.
In art, mimesis means when an artist tries to copy or imitate something they see in the real world. They might paint a picture of a mountain because they saw a real mountain and wanted to copy it.
Sometimes, artists use mimesis to create something that looks like what they see in real life. Other times, they use it to make something that's not exactly like what they see in real life, but still looks similar.
Overall, mimesis is a tool for artists to make art that reflects the world around them. Just like how you might try to copy your friend's jumping, artists try to copy what they see in the world to make cool pictures and sculptures.