The main language is French with a dialect called Central African French, which is easily understood by speakers of French. There are a lot of indigenous languages also. While French is the official language of the Central African Republic, only a few people in the country know more than a few words of it.
Sängö (also referred to as Sangro or Sangho) is the lingua franca and is spoken by most of the people in the Central African Republic (some 2000 have it as a mother tongue whilst 80% of the country have it as a second language). To find out if someone speaks Sängö, simply say Balâo (which means Hello), if they respond back with Balâo mïngï then you have found yourself a Sango speaker.
English is spoken by almost no one, even in the capital.