I am a PRN nurse. In the healthcare, it literally means temporary employment that could be one day or several days, usually filling in for a hospital or healthcare facility's unexpected gap in coverage.
In the past, my hospital would post the dates they need help and we would just turn in our availability. In another word, it would be okay if we don't want to work weekends or holidays. We just don't get paid.
Now work makes it mandatory to work weekends and holidays. Each tier comes with a pay cut. The highest tier requires people to work every other weekend, lots of weekdays and holidays. It is essential part time work without benefits.
I can either belly up and get the pay cut and work weekends and holidays, or just quit. Our hospital always cut corners. The money they save goes to the pockets of the managers, directors, VP and CEO.