As in most free-to-play games, Farm Heroes Saga has in-app purchases available to help you complete the more challenging boards. You don't have to purchase them, but they do help if you get stuck.
Lives

You only have 5 lives. Every time you are unable to complete a board, you will lose a life. If you connect with Facebook, you can ask your friends to give you more. Or, if you're the anti-social type, you can either wait until you get more or buy more from the store.
Gold Bars

Gold bars are the currency of Farm Heroes Saga and can buy just abut anything. The price ranges from $.99 all the way up to $109.99... for you really dedicated players.
Magic Beans

Magic beans is a secondary currency in Farm Heroes Saga and can buy boosters and bonuses for when you battle Rancid during boss levels.