gets the length of the string: Chad is cool
length = 12

adds the number 9001 to any number supplied!
9001 + 2 = 9003

How the fn above works is you define a name, i chose "adder" as the function name. It takes the argument in the php code and runs the function with that argument. For example, if you do adder(9) it takes 9001 in the function and adds 10 to it making it 9010.