Generally speaking, a pretrial conference is a court hearing where a prosecutor and a defense attorney get together and discuss whether a case is going to go to trial or whether it can be resolved through a plea agreement.
Pretrial conferences often take place in the weeks after a defendant is arraigned. The prosecutor will have provided the defense with all the relevant documents and police reports ahead of a pretrial conference so that the two can have a meaningful conversation.
If both parties reach an agreement, it is possible in some cases to resolve the case at the pre-trial conference. In such cases a judge will permit the defendant to enter a plea and will sentence the defendant at that time. In more serious cases, where additional time is needed to prepare sentencing arguments, the court will generally schedule a plea and sentencing hearing for a later date.