Imagine you have a piece of paper and you want to color it with crayons. You can either use one crayon at a time or multiple crayons at the same time. Mahler's Theorem talks about how many colors you need to use to color the paper in a certain way.
Mahler's Theorem says that if you want to color a particular pattern on the paper, there is always a way to color it using only a certain number of colors. This number of colors is called the chromatic number of the pattern.
For example, imagine you have a map of countries. You want to color each country a different color so that no two neighboring countries have the same color. This is called a "proper coloring". Mahler's Theorem says that no matter how many countries there are on the map, there is always a way to properly color the map using at most four colors.
So, Mahler's Theorem tells us that there is always a way to color things with a limited number of colors like a map or a piece of paper, while still keeping the colors from touching. It's like being able to color your pictures any way you want, but without making a mess!