The first option allows you toallow/prohibit cancellations of reservations with guests. The second option allows you toprevent abuse by adding a custom "limit" (e.g. 4 cancellations per week maximum).
Go to Admin > Users > Subscriptions > Cancellation rules to see these two new options.
Note concerning the option "Limit the number of cancellations to avoid abuse": the verification is done at the time of the cancellation attempt and is based on the number of cancellations made by the member over the last N days.