The A skills are natural aptitudes or things you were born with.
The V skills are vocations and learned/acquired skills.
The idea behind the skills is this. Everyone knows a little about everyone else’s job and by mixing and matching you effectively create what in other games would be character calsses. So a Ranger would have some combination of Hunter, Fighter, Mystic, Strength, Agility. A Guild Theif would have Theif, Agility, Socialite.
There will be cross-over between the skills especially the Vocational skills. Many stunts will also relate to at least pairs of skills.