The free cancellation period is the number of hours prior to the start of a booking, before which you can cancel for free. After that you get a 60% refund and the instructor gets the rest.
The instructor sets the free cancellation period for a skill. This means that different skills, even if taught by the same instructor, can have different ones.
You might find that some skills have a free cancellation period that is significantly longer or shorter than others. For example, if the instructor needs to prepare or buy in supplies before a booking, he or she might want to know well in advance about any cancellations. In this case, the instructor might decide that you only get a full refund if you cancel 48 hours in advance.