Imagine a playground swing. You push it and it goes forward and backward, forward and backward, over and over again, until it eventually slows down and stops.
Now imagine something called an oscillatory integral operator. This is a kind of mathematical machine that looks at functions - which are just things that take some input (like a number) and give you some output (like another number) - and makes them do a similar forward-and-backward kind of motion.
This motion is called oscillation, and it's kind of like what the swing does - except instead of swinging back and forth, the function is wiggling up and down, up and down, over and over again.
Why would we want to do this? Well, sometimes we need to study certain kinds of functions that have a lot of wiggling in them - and the oscillatory integral operator helps us do that.
It works by taking a function and using a special formula to "operate" on it in a way that makes it wiggle up and down. This formula involves some other functions, called kernels, which tell the operator how to do the wiggling.
Think of it like this: the operator is like a conductor, who's leading an orchestra (the function) in a piece of music (the kernel). The conductor waves his baton around, and the orchestra follows along, playing their instruments in time with the music.
The oscillatory integral operator is like that conductor. And just like a good conductor can make the music sound really great, the operator can make the function do some very cool things - like tell us about the shape of a surface, or help us predict what's going to happen in a system of particles.
So that's what an oscillatory integral operator does: it takes a function, wiggles it up and down, and gives us some really useful information. And just like a playground swing, it's kind of fun to watch - if you're into that sort of thing!