Which language should I study to improve my application programming language

Question

Apps

Answer 1

Top 5 programming languages of 2019
Python. Python is currently the fastest growing programming language on the mobile development market. ...
Kotlin. Kotlin is a relatively young native Android language that will probably replace Java at some point. ...
Swift. Swift is the next-generation iOS language. ...
Rust. ...
R.

Answer 2

C/C++ first even Python was written in C
Javascript
Python
Php for backend development Facebook uses some php in its development
Java
Kotlin