The juvenile court has three basic dispositional/sentencing options (all of which must focus on rehabilitation, not punishment:
1. place the youth on probation;
2. put the youth into a foster home;
3. put the youth into a residential treatment program.
In my experience, 97% of the cases fall into Option 1, 2% into Option 3, and 1% into Option 2.
So, in all likelihood, there'd be a period of probation. How long is anyone's guess ... probably 6-12 months or so. But courts can technically keep a kid on probation until his 19th birthday for this kind of offense. Terms of probation must focus on rehabilitation, and each youth is different and had different issues/needs so each set of probation rules is unique. On the one hand, it may seem obvious in an A&B case to order "anger management counseling", but maybe the fight was over a drug deal gone bad so the real "issue" is substance abuse, and the court's probation rules would focus more on that than on anger mis-management.
If this is a first offense in court, and if the victim was not badly injured, it's possible that the court will handle this case informally on the "consent calendar" process. This allows the court to actually dismiss the case altogether if the youth successfully completes probation terms.
So, this isn't the end of the world.