What programming language should I learn in 2017?

It's hard to answer this question, it depends on what you want to achieve. Java and Javascript still will dominate the market. There is couple of options which way to go:

1. Web development: If you want to be a web developer, you have to learn Javascript, because it's the only language all web browsers understand. Other than that you will need backend programming to serve websites. Most populars are : PHP, Javascript (NodeJs), Java, ASP, Ruby on Rails ..etc.. So, Javascript can be used both for backend and frontend.

2. Mobile development: Here we have mainly 2 options: IOS and Android. If you want to go IOS development you will need to learn Swift, this is new language developed by Apple. For Android you need one of these languages : Java, Kotlin, Go, C++. Go is supported from Android version 1.4, Kotlin is a new language developed just for Android. In addition you can use your web development skills - HTML/CSS/Javascript to develope mobile applications and compile them using tools like Cordova.

3. Game Development: Lot's of languages can be used for game development, the most famous engine is : Unity 3D ,you will need to learn C# or Javascript to develop games on that. There is another engine Unreal engine: you will need C++ to develop games with Unreal. C++, Java .. etc nearly any language can be used to develop if you are making engine from scratch. Meet boy is developed using C++ , Minecraft Java, limit is the sky.

4. Machine Learning: I would advice to learn Python for this path, but Java also would work.

5. IOT: To make Internet of things to need to program microcontrollers. Most popular language in this sector are C, C++ and Python

Good luck with what you chose and you just need curiosity and passion to be programmer.