Euros come in bank notes of 5, 10, 20, 100, 200 and 500 euros, and coins of 1, 2, 5, 10, 20, 50 cents, and 1 and 2 euros. The notes are identical across all "euro countries." The coins have the same design on the "tail" side, and a national design on the "head" side. However, the coins are valid in all countries, regardless of which of the 11 designs they carry. Therefore, you no longer have to change money when you cross borders within this group of 11 countries.
One euro is worth about 83¢ at the time of this writing. $1 = 1.20 euro. This is only a rough indication, as the exchange rate tends to vary rapidly. Suffice it to say that if you're from the U.S. and think of euros as dollars, you need to add about 20 percent (one fifth) to have a more accurate feeling for what things are costing you.
VISA is accepted almost everywhere (more so than American Express), including virtually every restaurant, department store, and gas stations. It is also accepted at major railway stations (including all the ones in Paris), subway stations, and grocery stores, but typically only for amounts above 8 euros ($10). Using VISA will ensure that your expenses are converted to dollars at very close to the day's official exchange rate, without surcharge, contrary to the exchange of cash or use of traveller's checks. You can get a VISA cash advance, in euros, from any bank that displays a CHANGE sign; this will also be converted to dollars at that day's rate, but remember that most credit card issuers give no grace period on cash advances, therefore you will pay a finance charge on the advance.
In recent years, however, the interconnection between ATM networks has greatly improved, so the best way to obtain cash while travelling in Europe is to use your ATM card. Most ATMs will first display a question about which language you want to use for the rest of the transaction, so language should not be a barrier.