Meals and breaks are regulated at a state level. However, non-exempt employees must be paid for all hours worked, and so, if they are at their work station(even if they are eating their lunch) during their lunch time, they are required to be paid for that time.
Non-exempt v. Exempt related to the FLSA. Non-exempt means the regulations of the FLSA apply to you. Exempt means they do not (though certain regulations still do to make it complicated). A common misconception is that salaried equals exempt, and hourly equals non-exempt.