public class Nth {

public static void main(String[] args){

int[][] arr = { {1,0,1,0},

{1,1,0,1},

{1,0,0,1} };

int n = Integer.parseInt(args[0]);

int[] col = new int[arr.length]; //[0,0,0,0]

for(int i = 0; i < arr.length; i ++){

col[i] = arr[i][n];

}

for(int i = 0; i < col.length; i++){

System.out.println(col[i]);

}

}

}

please explain, i dont get the part int[] col = new int[arr.length]; and col[i] = arr[i][n]; and why do we use for loop in this code