This hearing may also be called a pre-preliminary hearing or an announcement docket. Generally, these hearings are a time for your attorney and the prosecutor to discuss your case. The prosecutor will make a plea bargain offer which you and your attorney will discuss. If you decide to accept the offer, you would waive or give up your right to a trial and set your case for a date for you to plead guilty. If you do not accept the plea offer, you will have your case set for a preliminary hearing.
If you are charged with a felony you have a right to a preliminary hearing. A preliminary hearing is a court hearing where witnesses testify and the Judge decides whether there is enough evidence against you to order you to have a trial. If the court believes there is enough evidence to believe a crime was committed and enough evidence to believe you committed the crime (often, this is called "probable cause"), the court will "bind you over" for trial.
If the court does not believe there is enough evidence, the case will be dismissed. The prosecutor is not required to present all of their witnesses or all of the evidence they have collected. They are only required to present enough evidence to meet the "probable cause" standard.