Advanced Tactical Training is a special course for Starfleet officers. Officers must be recommended for this training. It is so difficult and challenging, in fact, that half of the class washed out each year.
This instructor was intended by the producers to be a reference to CommanderChakotay following the creation of Star Trek: Voyager. (Star Trek: The Next Generation Companion) Ro's article at StarTrek.com states this as part of her biography.  However, VOY: "In the Flesh" established that Chakotay resigned on March 3rd, 2368, i.e., already around the time Ro was released and reinstated. Either Chakotay continued as an instructor in some capacity despite his resignation, or Ro had already attended some courses of the Advanced Tactical Training before that.
Ro was later able to use the training to trick the USS Enterprise-D and "steal" supplies from it while working undercover with the Maquis before actually defecting. (TNG: "Preemptive Strike")