Single characters in Chinese are words, but those words often aren't specific enough by themselves. The character for goat, 羊, is perhaps more accurately "something goat-like". A sheep would equally qualify for this character and so this year could be a goat or a sheep. Extra characters get added to clarify which is meant. Our billy goat is trying his best not to get rooted to the ground back in 2015, but it's hard with the birds and bugs mistaking him for part of the forest.