I answered to this question on Quora:
"When it is said that 1 bitcoin is worth a certain amount of money? Does that mean that 1 bitcoin is literally worth that much money? How exactly does a transaction between a bitcoin and real money take place?"
My answer:
First of all, bitcoin is real money.
And yes, if during a transaction it’s said that 1 BTC is worth X $, it’s litterally worth X $ in this transaction. The price of bitcoin is continuously negotiated (like the price of euro vs dollar).
Also, buying bitcoin is not the only way to have bitcoin. You can, buy, sell, earn, give for free, steal a bitcoin (or a fraction of it) like any other currency.
You can go to a friend, give him your bitcoin, and he could give you a certain amount of cash, or his car, his wife etc.
A transaction between bitcoin and real money is one specific case, and can take place in many different ways.
The most common way to buy/sell bitcoin for fiat currency (US dollar, euro etc) is through an exchange (Coinbase for example). You give your money to the exchange, and they give you bitcoin. Easy.