The serona was a rite of passage and five year military requirement for Romulans upon reaching adulthood.
During this time they recieved basic military training, dictated by the Romulan High Command. Personal weapons training, hand to hand combat and military regulations were the bulk of core training received.
Most "serona scruffs" were looked down upon by careeer military personnel, and assignments are normally menial or mind numbing, freeing up "real soldiers" for more important tasks.
Guard duty, engineering and medical support were some of the best assignments to be hoped for at this time. Highly intelligent members would occassionally be assigned to astronomical facilities, learning to map the Endless Sky.
Those of a noble background were not excluded from the serona, nor did they recieve preferntial treatement or assignements. This was considered the one time in their lives they would be treated like anyone else, though in practice they experienced a rougher time.
Exemplary performance during the serona can result in an officer's commission and occasionally gain admission to the Romulan War College.