The voltage in Switzerland, as in most of Europe, is 230V/50 Hz.
Switzerland uses type C (2-pin) and Type J (3-pin) plugs. (Type C 2-pin plugs also fit J sockets.)
Most power sockets are designed for three pin round plugs. The standard continental type plug with two round pins, applied for many electrical travel products, may be used without problem. Adaptors are available in most hotels.