what programming language use in game development?

Answer 1

All the language can be used in game development. Some game engines have their own language, for example UDK3 use unreal script. Anyway, the language for game depends on the systems, developing tools, and the types of games.

Answer 2

java (for Android) Swift ( for iOS)
for both: python, c++

Answer 3

You can use Unity to design games, then program them in C#.