I want to learn about the more advanced parts of game development(2D games)

I know the basics, like getting a character to move on the screen, adding entities to tables and drawing them to the screen, then removing them from the screen when I need to, using the mouse, exiting the game, implimenting physics...but it all just feels so basic and amateurish when I create a game with what I know. When I watch live streams of people making 2D games I hear them talk about stuff that goes way over my head like rendering 2D graphics, vector math, 2D lighting, mesh filtering, ray casting, the list goes on.

What I want to know is how can I learn to make my games better, use more advanced techniques, so they don't seem so amateurish. I know you guys are going to say to practice practice practice, but its gonna be hard to practice something if I don't know what to practice. So are there any lists of what I should be learning(programming-wise), books on advanced game development/design, or anything like that?

BTW I used unity a bit before, but now I am using Love2D and I love it way more than Unity. For some reason I think I like frameworks better than engines. Also I love lua scripting and my main OS is Linux, so its better than C# for me.