Fixed point in mathematics is like finding a spot on a number line where the number stays the same after a certain operation is applied to it. Let's think of our number line as a line of ants marching in a direction.
Now imagine we tell the ants to start counting by threes, so the first ant would say "3", second ant "6", third ant "9" and so on. If we just look at the number line, we can see that 9 is a fixed point for this operation because after counting by threes, we end up at the number 9 and if we continue to count by threes from 9, we'll always get 9 again.
Another example of a fixed point is "0" for multiplying by 1. If we multiply any number by 1, the result will always be the same as the original number (because 1 times any number is that number), so any number is a fixed point for multiplication by 1.
Fixed points are important in many areas of math and science, from optimization problems to chaos theory. They can help us find solutions to equations and understand how different systems behave over time.