A salutatorian is a graduate who finished with the second highest rank in his or her class. Only the valedictorian did better.
Being the salutatorian of your graduating class is a great honor. Traditionally, the salutatorian gives the opening remarks at the graduation ceremony. So, just as a salutation is a greeting, a salutatorian is responsible for offering a formal greeting at the event. Having been a salutatorian looks great on a resume, as long as you spell it correctly.