Some societies also have minorities who do not speak the official language. Especially in countries in which immigration has played an important part in history, you can find several spoken languages. In the United States Spanish is the most common language next to English, but there are hundreds of thousands who speak Polish, Russian or Italian because their families have gone to the US during some point in history.
All over the world, millions of translators translate one language into another. Such people are especially needed in international organizations, like the United Nations or the European Union.