Okay kiddo, do you know what an abstract painting is? It's when someone paints something that doesn't look like anything in real life, it's just a bunch of colors and shapes that the artist put together to make something cool to look at.
Well, abstract illusionism is a type of painting that takes abstract art to the next level. The artist uses shapes and colors to make it look like the painting isn't just flat on a canvas. It tricks your eyes into thinking there's something more going on, even though it's just paint on a surface.
Imagine you're looking at an abstract illusionism painting of a triangle. The artist used shadows and shading to make it look like the triangle is popping out of the canvas and you could almost touch it. But really, it's just paint that the artist put down in a special way to make your brain think there's more going on than there really is.
So basically, it's like a magic trick, but with paint and colors instead of a person doing a cool trick. It's a way to make art really interesting and fun to look at!