Hi! Please, carefully check this links:
For mobile development:
OK kindly there are lots of frameworks developed for Android programming since Android is also became popular. I'm not covering only Android but this days ios is also become popular that mobile programming is now become a well possibility in IT markets. Traditionally for Android Java and kotlin is best languages and so on for ios swift and objective-c.
But lots of framework provides both of services without using the different codes in different environments. Instead it use same code and compile it for two different platforms. Like Xarmin(c#) , flutter(dart) , React- native(JS, CSS, HTML).
ReactNative, for cross platform mobile app