The purchase of a call option is a long position, a bet that the underlying futures price will move higher. For example, if one expects corn futures to move higher, they might buy a corn call option. The purchase of a put option is a short position, a bet that the underlying futures price will move lower. For example, if one expects soybean futures to move lower, they might buy a soybean put option.
When buying or selling options, the investor or trader has the right to exercise that option at any point up until the expiration date - so simply buying or selling an option doesn't mean you actually have to exercise it at the buy/sell point. Because of this system, options are considered derivative securities - which means their price is derived from something else (in this case, from the value of assets like the market, securities or other underlying instruments). For this reason, options are often considered less risky than stocks (if used correctly).