Explanation to a note.

Hey there,I was reading a note and I came up across a couple of things I'd like to have explained to me.
My first question is, what is the purpose of the 2 besides the star on line 6 and the bracketed "int n"? Thanks in advance. This is not an assignment,just a note from the internet.

Code:

---

/* A void function with one argument */
#include <stdio.h>

/* a void function returns nothing */
void
stars2 (int n)
{
int i;

/* a loop displaying a star at
each iteration */
for (i=1; i<=n; ++i)
{
printf ("*");
}
/* change line after each series */
printf ("\n");
}

int
main (void)
{
int a;

a=10;

/* the argument may be a constant,
a variable or an expression */

stars2 (20);
stars2 (a);
stars2 (a+2);

return (0);
}

---

"stars2" is the function's name, while "int n" is it's argument. Functions in C