When we see things, sometimes we think they are real, but they might not be. For example, when we see a stick in the water, it looks like it's bent. But when we touch the stick, we can feel that it's not really bent. This is called an illusion.
The argument from illusion is when we use illusions to prove that something isn't real. Let's say we see a ghost. It might be scary and seem real, but it could just be an illusion. If we use this argument, we say that since ghosts are just illusions, they aren't really there.
But sometimes, the argument from illusion can be tricky. For example, if we see a person far away and think they're a monster, but when they get closer we can see they're just a regular person, that doesn't mean that everything we see is an illusion. It just means that sometimes we can be mistaken.
So, while illusions can be cool to look at, we have to be careful when using them to argue that something isn't real. Sometimes things really are there, even if they look a little weird.