Hello dmesantos.
“void” is not a “command” in this case.
It is the type of the variable the function returns.
Every time you declare a function in c++, you have to specify what it takes (input) and what it returns (output).
Strictly speaking the function is: void PrintIntro(void)
Here is a link, which describes functions very well.
http://www.cplusplus.com/doc/tutorial/functions/
If you scroll a bit down, you will find the section “Functions with no type. The use of void”.
But I recommend to read all the text, then you will understand “functions”.
Hope that helps & happy coding.
Chris