Depends on what you want to do.
JavaScript is a great one for 2020. You can do backend (Node.js), frontend (React/Angular/Vue), or mobile (React Native) with this language.
Java is still in high demand for services and backend roles.
Python is great for big data and ML.
The thing about programming is that you can pick up just about any language once you learn the fundamentals of programming in general. So, variables, objects, data structures, decision structures, loops, etc.