Row and Colums excercise

Question

 In the below program if i give n=3, i get 1,2,3 equally in rows and colums. My question is how is the system identifying the row and colums...

 

int n = int.Parse(Console.ReadLine());

for (int row=1 ; row<=n; row++)

{

for (int column = 1; column <= n; column++)

{

Console.Write(" " + column);

}

Console.WriteLine();

}