Hi!
A rational number is going to be one that terminates. An irrational number is going to be a number that either repeats forever or is simply never-ending gibberish!
An example of an irrational number would be: 5.123812847981375483545832660780946780596780704569856478 (And it just goes on... and on... and on... forever and ever... lost in the abyss......)
A rational number, however, will terminate! This means instead of going on forever and ever, it has an end.
When we turn the fraction 3/5 into a decimal, we get 0.6. Does this look like a rational or irrational number to you? =)
Hopefully, this helps! =)