using System;

using System.Xml;

using HtmlAgilityPack;

public class Program

{

    public static void Main()

    {

        var html = @"<div class='XKa d-k-l'><span class='VTb d-k-l'></span></div><div class='pha d-k-l'><div><div>Hello World </div></div></div>";

        var HTMLContent = new HtmlDocument();

        HTMLContent.LoadHtml(html);

        var item = HTMLContent.DocumentNode

                    .SelectSingleNode("//div[@class='XKa d-k-l']/following-sibling::div[@class='pha d-k-l']").InnerHtml;

        Console.WriteLine(item);

    }

}