This mod adds new player models and textures that make players look like ponies, in the style of the TV show "My Little Pony: Friendship Is Magic". Once the mod is installed, you and all other players will look like ponies in both singleplayer and multiplayer. Players who aren't using a special pony skin will look like one of the background ponies from the show (as the default player skins are not fully compatible with this mod).
Pony skins are backwards-compatible with the original player model, so they look fine to any player who doesn't have the mod installed (those players just won't see the pony models). You can be an earth pony, a pegasus, a unicorn or an alicorn. Pegasus ponies flap their wings when flying, and unicorns hold items in the air in front of them as if by magic.