Like any other programming language, there are lots of ways people can learn Lua. If you have a lot of time, some knowledge of coding and are willing to put in the effort, there are thousands of YouTube videos and free online tutorials (of various quality admittedly) that you can teach yourself with. If you prefer a quicker and more structured learning method, there are a few affordable online Roblox classes that you can take that can bring you up to speed and creating games sooner rather than later.