Okay kiddo, a cartographic projection is kind of like a way to take a picture of the whole world and put it onto a flat piece of paper or a screen. You see, the Earth is round, like a ball, but when we want to see the whole thing at once, we need to make it flat.
Imagine if you have a big, round orange and you want to make it flat so you can see all of the parts at the same time. You might take a knife and cut the skin into pieces and then lay those pieces flat on a piece of paper. This is kind of like what a cartographic projection does with the Earth.
There are lots of different ways to make a cartographic projection, just like there are lots of different ways to cut an orange. Some projections make certain parts of the Earth look bigger or smaller than they really are, like when you squish a balloon and some parts get bigger while others get smaller. Other projections might stretch certain parts of the Earth out so they fit on a flat surface better, like when you stretch a piece of dough to make a pizza crust.
Each projection has its own benefits and drawbacks, depending on what you want to use it for. Some projections are better for seeing how big different countries are, while others are better for showing how to get from one place to another on a map.
So, that's what a cartographic projection is - it's a way to make a picture of the whole world that fits onto a flat surface, and there are lots of different ways to do it!