I am trying to see if I am understanding this right for a homework assignment. Can anyone please help.

void fun ( int first. int second) { //If I am right we are declaring variables
first += first; // addidtion assignment what does it mean??
second += second // same question
]

void main() { //is this creating an array?
int list [2] = {1,3}; // creates a list named 1 and 3 or is it the values of the list???
fun(list[0], list[1]); //this calls fun
}