Understanding this Reference usage in between two different classes

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace Apps

{

    class CallingAnotherClassMethod

    {

        private string[] items = new string[5];

        public int k { get; set; }

        public int i { get; set; }

        public int j { get; set; }

        //public int i=5,j=12;

        public void CallingMethod()

        {

            k = 10;

            j = -7;

            i = 12;

            //Here this is used to pass the fields like k,i,j to the another class methods.

            Console.WriteLine(ObjectReferingToCallingMethod.objectCreationOfCallingMethod(this));

            //Also we are calling Method with class name because the method is static in the below class.

        }

    }

    class ObjectReferingToCallingMethod

    {

        public static int objectCreationOfCallingMethod(CallingAnotherClassMethod cl)

        {

            return 10 * cl.k*cl.i*cl.j;

        }

    }

    class UnderstandingThisReference

    {

        public static void Main()

        {

            CallingAnotherClassMethod obj = new CallingAnotherClassMethod();

            obj.CallingMethod();

        }

    }

}