Okay kiddo, so let's start with what a series is. A series is just a list of numbers added together. For example, 1 + 2 + 3 + 4 + 5 is a series.
Now, a rational series is a special type of series where the numbers in the list are actually fractions. Fractions are when you have a number on the top (called the numerator) and a number on the bottom (called the denominator) separated by a line.
So a rational series might look like this: 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + ...
Do you see how each number is a fraction with a denominator that gets smaller and smaller? That's what makes it a rational series.
There are some special things about rational series that make them interesting. One is that if you add up all the numbers in the series, you might actually get a whole number! That might sound strange, since we're adding lots of fractions together, but it's true.
Another interesting thing is that there are some special techniques we can use to figure out what the sum of a rational series is, even if there seems to be an infinite number of fractions. These techniques have to do with patterns in the denominators, and can be really useful for solving all kinds of math problems.
So that's the basics of what a rational series is. It's just a fancy way of adding up fractions, but it can lead to some pretty cool math discoveries!