⟩ What was the best job you ever had? Why?
She is wanting to know if what you really enjoy doing is something you will enjoy doing in the salon. If you loved being a number cruncher and sitting at a desk all day you probably won't like being a creative, stand on your feet all day hairdresser. In her eyes, maybe you are not the best suited person for her open chair.
However, if you worked at PetSmart and enjoyed running around the store and helping customers with their beloved pets the interviewer could see how those activities could easily translate into beauty career activities.
Choose a job you've had where the activities are similar to those in a salon, like, customer service, sales, being active rather than sitting, and multi-tasking.