A hedge is a living fence made of closely planted bushes, which, as they grow and get trimmed and shaped, form a wall of green.
Hedge can also be used as a verb. If you someone asks you a question and you hedge, you're avoiding a straight answer. If you hedge your bets, you're trying to minimize risk or loss — that is, you're trying to cover yourself no matter what happens. If you're not sure, for instance, what your boss's political views are, you can hedge your bets by not revealing yours.