To empanel is to select a group of people for a jury. If you're empaneled, you're part of a jury. Congratulations.
Jury duty is one of those things all adults have to do as members of a democracy — show up in court to possibly be a member of a jury in a trial. When you're added to a jury, you're empaneled. This is an old-fashioned word that comes from an older sense of panel, which was the paper on which names of jury members were written. Lots of people report for jury duty but aren't empaneled, meaning they aren't selected.