A language page is more useful if it says where you'd speak it. Below is the short map. Open a language for countries, cities, and the variety the app uses.
Europe
German, French, Spanish, Portuguese, Russian, Ukrainian, Turkish
German covers Germany, Austria, and much of Switzerland. French and Spanish spill over borders. Ukrainian is the state language of Ukraine. Turkish is Turkey, plus large communities in Germany and the Netherlands.
The Americas
English, Spanish, Portuguese, French
Spanish is the daily language from Mexico to Argentina, with Brazil as the Portuguese exception. English and French share Canada. English also runs most of the US and a good part of the Caribbean.
Africa
English, French, Portuguese
These are school, court, and city languages next to local ones. English in Nigeria and Kenya, French from Senegal to the Congo, Portuguese in Angola and Mozambique.
East and South Asia
Chinese, Japanese, English
Mandarin is what you'll use in mainland cities. Japanese stays almost entirely in Japan. English is the extra language in India, Singapore, and most international airports.