There are several problematic issues in your code:

1. int[][] and int[,] are different. You need to choose one of them and be consistent.
   I’ll assume you picked int[,] for the rest of the answer, but it could be adapted to int[][].
2. When you access an int[,] element you should use operator[,] (not [][]) – so array[i][j] should be array[i,j].
3. Array indices are zero based, and so array[i][4] (even if you choose int[][] will go out of bounds – the second index should be in the range 0..3.
4. Array dimensions are also zero based. In your outer loop you seem to attempt to iterate over the first dimension, so you have to use array.GetLength(0), not array.GetLength(1).
5. This is not causing an immediate error, but array is rather a bad name as it could cause conflicts, it is better to choose another name (e.g. arr).

A fixed version:

public class Program
{
    public static void Main(string[] args)
    {
        testing Test = new testing();

        if (Test.test(Test.arr) == true)
        {
            //code
        }
    }

}
class testing
{
    public int[,] arr = {{10,0,25,7},
                        {5,0,30,10}};
    public bool test(int[,] arr)
    {
        int count = 0;
        for (int i = 0; i < arr.GetLength(0); i++)
        {
            if (arr[i,3] <= 0)
            {
                count++;
            }
        }
        return count == arr.GetLength(0);
    }
}

Side notes:

1. You mentioned that you want to test to see if all columns in rows in a array are the same number. But the logic you posted is quite different.
   Anyway based on the comments above you can modify the logic according to your needs.
2. Your test method code does not actually access the array member, but rather the method parameter.
   Therefore you can either make it a static method, or remove the array parameter so that the method will access the member.