The abbot is a small addition that comes bundled with the second edition of the base game. He's a second monk-shaped figure, but with an option the regular monk never had.
Where the abbot goes
Place the abbot like a regular folk, but only on a cloister (where he acts as a monk) or on a garden — a new tile type that scores exactly like a cloister.
Bringing the abbot home early
Instead of placing a tile on your turn, you can retrieve your abbot from a cloister or garden and score it right then for its current value — 1 for itself plus 1 per surrounding tile. He comes back to you, ready to be placed again.
Logging it: just use the regular Cloister entry. It already asks for the count, so an abbot pulled at 5/9 surroundings logs the same way as a partial cloister at end-game.
End of game
If the abbot is still on the board when the last tile is placed, he scores like an incomplete cloister: 1 for himself plus 1 per neighbor. The End-game wizard will collect this for you.