"Futures" is a word people use to refer to the trading of futures contracts. A futures contract is a contract that carries an obligation to buy a specific quantity of something on a specific date. Of course, that date is going to be in the future, thus the name.
Soooo, what does that mean? Here's an example: I'm a farmer and I want to make sure my corn will be sold next year. You tell me you can give me a contract that says you will definitely buy it for $600 on November 20th. Now, I might think it will be worth $800 at that time, but the security of having it sold is worth it to me. That's the origin of the futures contract.
Today, you won't be writing and signing papers, meeting with anyone, or getting bushels of corn delivered to your house. The creation, purchase, and sale of futures contracts is electronic and looks very much like securities. Rather than buying shares of stock, you might buy futures contracts that speculate about a future price of that stock. You can see why charts representing the value of futures contracts would follow charts of the actual thing, possibly with more volatility.
It is possible to write a futures contract for pretty much anything you can buy. In the futures market, there are some traded contracts that are more standard than others, many of them being commodities. These have become more standard simply because they have more liquidity than others. Futures contracts for currencies are also available.