Switzerland has four national languages: German is spoken by two-thirds of the country, and French is spoken by close to one third of the population.
Italian is important in the south of the country, while Rhaeto-Romance is a minority language spoken in the eastern alps.
Although English is widely spoken, it's a good idea to learn the local language of your region. Knowing even just a few phrases will help in daily life and creates plenty of goodwill.
Tip: Language classes are also a great place to meet new people and make friends!