Okay kiddo, so have you ever heard of a puzzle that has different shapes and sizes of pieces that fit together perfectly to create a picture?
Well, in math there is something called a Schauder basis that is kind of like a puzzle of functions that fit together perfectly to create other functions!
Let's imagine that we have a big box of functions (like a big box of puzzle pieces) and we want to create other functions by putting together different combinations of those functions.
A Schauder basis is a special set of functions (puzzle pieces) that all the other functions can be made out of by adding and scaling them (like putting different puzzle pieces together in different ways and sizes to make a big picture).
This special set of functions (puzzle pieces) is chosen in a way that makes it easy to work with and to create other functions (a good puzzle has pieces that are easy to work with and fit together).
So, Schauder basis is a way of organizing functions into a set that is easy to work with and create other functions from by adding and scaling them in different ways.