You will be auditioning for at least two faculty members in your area, in a 15-20 minute time slot. Your audition will include performance of the required repertoire as well as interview-style questions about your background and academic interests.
Keep in mind that the music faculty members at your audition have all auditioned themselves and understand how stressful the process can be. They want to hear you at your best, so they all strive to put you at ease and welcome you.