Not understanding how default parameter values work

Question

static int Pow(int x, int y=2)
{
int result = 1;
for (int i = 0; i < y; i++)
{
result *= x;
}

return result;
}

static void Main(string[] args)
{
Console.WriteLine(Pow(6));
//Outputs 36

Console.WriteLine(Pow(3, 4));
//Outputs 81
}

is the Pow method defaulting to multiplying itself by the argument value here?

Cannot get my head around this! Any help is appreciated.