you are getting error becuase you have declared ss variable in foreach loop and using ss variable out of function scope

athelli_reddy

foreach (DateTime t in vv)
                    {
                       
                        String ss = GetPrettyDate(t);
                        newList.Add(ss);
                       
                    }

this.ListView1.DataSource = newList;
                    //HERE I WANT TO BIND DATA TO DateDisplayLabel like below
                    l.Text = ss;  --- But I am getting an error message.
                    this.ListView1.DataBind();

just  declare string ss variable before foreach loop , and do this

String ss = "";
foreach (DateTime t in vv)
                    {
                        
                       ss = GetPrettyDate(t);
                        newList.Add(ss);
                       
                    }

i hope this helps you