Okay, imagine you are playing with some blocks. You have different colored blocks and you can stack them on top of each other. But for some reason, you can only use a certain number of blocks of each color, and you have to arrange them in a really specific way.
Now imagine you have some equations that describe these blocks and how they can be stacked. These equations are called differential equations, and they can be pretty complicated.
The Kobayashi-Hitchin correspondence is like a puzzle where you try to find a special combination of blocks (or a special solution to the differential equations) that meets all the requirements at once.
It turns out that this puzzle is related to a bunch of other puzzles in math, like geometry and topology. So when you solve the Kobayashi-Hitchin puzzle, you also learn something about these other puzzles too.
But don't worry if it's still a bit confusing. Even some really smart grownups might not fully understand the Kobayashi-Hitchin correspondence yet!