I recommend starting with Lua. It's fast and teaches you a lot of concepts and encourages clean code without being difficult. Python isn't bad either. Lua can be practised in two game settings: Roblox and Computercraft, the latter I used.
Once you get a good grasp of one language, learning a new one will be much easier than you'd think since you already get the fundamentals and you're just translating "Okay, so if I would do this in Lua, how would I do it in X?" and simply learning syntax.
Other recommendations are Java/C#: They are faster than Python and are very widely supported on multiple platforms, and learning either of those will make learning C/C++ easier - and they are really the big language for games, anything involving graphics rendering and especially games/programs on old platforms, ie. homebrew.
Bottom line: if you want to go for an open source project or a program for modern PCs, then Python and Lua are a good bet. Python is flexible, simple and widely supported. Lua is similar, though a bit less popular and significantly faster. However, if you want to dive into the deep end, I recommend C or C++. C/C++ introduce computer science concepts like memory management, and they're difficult languages especially to start with, but if you can grasp them you will have exceptional and basically unparalleled performance (aside from assembly/machine code) and it's both good for performance-driven applications as well as for squeezing out the most from hardware without writing assembly, which takes much longer and is extremely difficult to interpret without a good understanding.