Okay, so imagine you're playing with building blocks, trying to create something cool. But sometimes you get stuck and don't know how to put the blocks together. That's where the GNU Scientific Library comes in.
It's like a big box of tools for grown-ups who like to use math and science to solve problems. With this library, they can do complex calculations and solve equations that would otherwise be too difficult for them to do by hand.
It's like a helper that does the hard work for them, so they can focus on creating something awesome with their building blocks.
And just like how there are different sizes and shapes of building blocks, the GNU Scientific Library has different functions and tools for different types of problems. Some are for working with numbers, others are for working with matrices, and so on.
But just like how you need to have building blocks to play, you need to know how to code to use this library. So, it's something that is used by grown-ups who are good at math and programming.