Abilities keep track of a person's skill set, qualifications, and completed training. Abilities help you staff your duties with people who are capable or sufficiently qualified to do the job.
Abilities are managed in Settings. Add to, and remove from, the specified field to control which abilities are assignable in Sheep.
Once you've added a set of abilities in Sheep, you can assign relevant ones to your staff, volunteers, etc. Anyone with abilities assigned to them will appear in the Staffing Calendar.
Remove selected abilities from their abilities field to prevent the person appearing for particular duties e.g. qualification is out of date.