The Executive Assistant, or EA, is a civilian liaison between Starfleet and civilians when they are present on a starship, starbase or facility.
They are a division head in the Command Department, and work closely with the Executive Officer to make sure the civilian population is represented to the Commanding Officer. They commonly work with the Morale, Welfare and Recreation Officer and Training Officer.
Under his purview are the education of any children present, civilian work assignments, supply, berthing issues and a host of other day to day issues Starfleet personnel do not have the time for.
Pi'riah was the USS Camelot's EA at the time of Operation Return.