@niveditakumari 

If you are using DateTime field please adjust the script as follow:

var hiringDate = current.u_hr_hire_date;
var hiringDateGd = new GlideDateTime(hiringDate);
var currentDateGd = new GlideDateTime();
var hiringYear = hiringDateGd.getYearUTC();
var currentYear = currentDateGd.getYearUTC();
var experience = currentYear - hiringYear;
template.print(experience);