An indictment is a list of the counts (known more generally as charges) that you are facing. The prosecution file an indictment as the formal beginning of a matter before the higher Courts.
A copy will be sent to your lawyers. The filing of the indictment is often done on a day other than when you are at Court. As it is a formality, you do not need to be there for the filing of the indictment unless you are already on bail to appear on that date.