It depends. If you want to work in AAA game company, learn C++, C# or Java would be necessary. And most of game companies right now is using the existing game engine e.g. (Unreal, Unity, etc.) and it's using that languages.
If you want to work for indie game or just by yourself, technically, you can use whatever your language you want learn (Ruby, JS, Python, whatever.)
I think, it would be better to focus at existing game engine(or libraries) rather than the programming languages itself. The free one and with strong community would be a good start! I mean, you don't need to build it from scratch, it's just hella time consuming. :D
For me personally, I'm using Ruby2D (free) for prototyping simple app. And RPG Maker VXAce (paid) because most of my project is mostly focused on retro-RPG. And it's all written on Ruby.
For building a game from the scratch, I'm using Godot Engine. and it's using GDScript (Python-like custom script) and you can mix-it up with C++ if you need some performance. And it's free.
The best place to start with it is right here! Here you will find courses of the languages you should learn for games development(C++, C#, Java, etc). Have in mind that this courses are the foundamentals to go deeper into any programming skill.