Okay kiddo, so truthmaker theory is a way of helping us understand what makes something true. Let's say you draw a picture of a red apple. If someone looks at that picture and says "yes, that's a red apple!" then they believe that what you drew is true. But what is it that makes that picture true?
Well, according to truthmaker theory, there has to be something in the world that corresponds to that picture. In this case, there has to be an actual red apple somewhere that the picture is representing. If there wasn't a real apple, then the picture wouldn't be true.
Does that make sense so far?
Now, truthmaker theory doesn't just apply to pictures - it can also apply to statements, like "penguins can't fly". For that statement to be true, there has to be some fact or thing in the world that makes it true. In this case, the fact is that penguins' bodies and wings aren't designed for flying like other birds are, so they can't fly. If that fact didn't exist, then the statement wouldn't be true.
So truthmaker theory is basically a way of explaining that when we say something is true, there has to be some part of reality - like an object or a fact - that backs up that claim. It helps us understand the relationship between the things we say or think and the real world around us.