[Nero_3D]

In that case it tells the function that this variable should be passed by reference

That means if you change the variable inside the function it will also change outside

pawn Code:

main() {
    new
        var1 = 3,
        var2 = 3
    ;
    MyFunc(var1, var2);

    printf("%d, %d", var1, var2); // 3, 5
}

MyFunc(value, & reference) {
    value = 5;
    reference = 5;
}

Array are always passed by reference