Historically, Druids had a place in pagan Celtic society, but in fiction they are usually mystical beings charged with keeping nature safe. They usually live as hermits in the forest, coexisting with animals and protecting them from the influence of the outside world.
The druid's communcation with nature allows it to talk with animals and use them for its own gain.
If your opponent has an animal that you want, the Druid's ability can be used instead of attacking/discarding in order to steal their animal. The Chicken is definitely a card you want to use immediately, giving you extra cards to hopefully place in your village next turn. Other cards such as the Pig or Horse should be placed into a village if you can, as they will give you a number of strategic options on your next turn.