The HR sent you the an interview invitation and than you have to appear for the interview on the date that's mention in the mail. There will be three rounds, In initial screening they will ask about basic info and all that. Second round will be technical and third round will be HR. You will be hired as a technical help desk, all the job designations are just to attract people. These people are grammernazis. if you want to persue your career in IT field this place is not for you, you will only be helping people with their day to day life technical problems.