The most common card in Switzerland is Maestro, a debit card issued by most banks. Visa, Diners Club and American Express cards are also available.
You can obviously use a credit or debit card issued outside of Switzerland. Swiss ATMs tend to accept most common types of card (Visa, Mastercard, Maestro, Cirrus, etc.). Bear in mind that you may be charged a fee for withdrawing money, have a daily maximum you can withdraw and also don't get a very good exchange rate from your home currency. If you are going to stay in Switzerland for a while, it might be more convenient to move your money to a Swiss account, make all transactions locally and receive statements directly from a Swiss bank.
The currency of Switzerland is the Swiss franc (Schweizer Franken - franc suisse), which is abbreviated as CHF (also sometimes as Sfr.). One franc is divided into 100 cents (Rappen - centime).
Swiss francs can be easily exchanged to and from most foreign currencies at banks, ATMs, in shopping centres and airports. If you are transferring money abroad, you may get a better exchange rate from the post office or money transfer services than a bank.