Ok kiddo, let me explain this Hilbert-Bernays paradox to you. It's like a puzzle that mathematicians were trying to solve.
Think of a big box with lots of smaller boxes inside it. The big box is like a math theory, and the smaller boxes inside it are like the rules or axioms that make up that theory.
Now, imagine if one of the smaller boxes said "this box is false." That's like saying "this rule is fake." But if that's true, then the big box (the theory) is also false, because it's made up of all the smaller boxes (rules).
This creates a paradox, or a big problem, because if the theory is false, then everything we thought we knew about it might also be false.
So mathematicians were trying to figure out how to fix this paradox. One solution was to create a new, bigger box that included the original theory and also rules about how we can talk about it. This way, even if one of the smaller boxes says "this box is false," we can still talk about the theory in a consistent way.
Does that make sense, little one?