The box art
Sheep & Hills is an expansion that was released by Z-Man Games in July 2014. This 9th large expansion includes 18 landscape tiles, 18 sheep tokens, 2 wolf tokens, 6 shepherd meeples and 1 cloth bag.
The Tiles
Out of the 18 tiles of the game, 8 include vineyards, 8 include hills.
Sheep and Shepherds
A Shepherd may be placed on a field (doesn't matter you already have a farmer or not, according to the official game rule at http://zmangames.com/rulebooks/Carcassonne_Exp9.pdf). After the shepherd is placed, take a sheep token from the bag and place that token next to your shepherd. There are also 2 wolf tokens mixed in with the sheep so if you take a wolf, you must retrieve your shepherd and return the wolf token to the bag. After that turn, whenever you place a tile that adds to the farm that has the shepherd, you can choose to place a follower (or not) first, then you may either take a sheep token from the bag (called "grow the flock") or trade in all your sheep tokens for 1 point per sheep (called "gather the flock"). Similarily, if you take a wolf, you lose all your existing sheep, and you must retrieve your shepherd and return all tokens to the bag. Note you have to "gather the flock" before the game ends - shepherds in play at the end of the game score no points.
Vineyards
On eight of the tiles, there are vineyards which if placed bordering a monastery, they add 3 points to overall value of the "complete" monastery. A single vineyard can add points to multiple adjacent monasteries (i.e. it can be counted several times for different monasteries). Note at game end, an incomplete monastery does not receive any additional points from its neighboring vineyards.
Hills
Place and occupy: If a player draws a Hill tile, he/she immediately draws another tile (without looking at it) and places it underneath the Hill tile. Then, the player may place a follower onto the tile according to the normal rules. The hill is not itself a feature, but affects all features on its tile (city, road and field).
Hills during scoring: Any follower placed on a Hill tile breaks ties in favor of its owner. That is: when a feature (city, road or field) is scored, and two or more players are tied for most followers, a follower that occupies a Hill tile will break the tie in favor of the player who owns it. This player alone will score points for the feature.
If there is no tie when a feature is scored, the hill offers no other bonus. A follower on a hill is returned to a player’s supply after a feature is scored just like a normal follower. A follower occupying a hill is also eligible to break ties during end game scoring (for fields and incomplete features).