Oncology/Hematology Lab PRN

Been a medical technologist for about 8 years and have mostly worked as a generalist at large hospital systems during that time. This position is PRN (Days) and it’s at a smaller cancer center type laboratory that’s open during normal business hours.

Has anyone ever worked PRN? What kinds of questions do they ask in an interview for this type of role? I’m not sure what to expect for a PRN schedule, is it flexible or more like being on call where I have to be ready to come in within a certain time period of being called?