Do what it says. For the result, lowercase a's represent a lowercase letter and uppercase a's represent an uppercase letter. For example: If you put in "TeSTinG," you will get "AaAAaaA." So letters 1, 3, 4, and 7 are uppercase while letters 2, 5, and 6 are lowercase. There is also a button that says "Randomize." This button gives you a random string of uppercase and lowercase letters.
IMPORTANT: If you use this system for your own projects, I am fine with it AS LONG AS you GIVE CREDIT.