Like others have said it depends on the field you want to code for and language choice. The field might inform your language choice.
I’d highly recommend python as your first if you’re just looking to get stuck in. It’ll teach good fundamentals, it doesn’t have a steep learning curve and it has a very wide set of applications plus loads of community support. This website is what I recommend to anyone wanting to learn python: https://futurecoder.io/
Good luck!
+1 for notesnook, self hosting coming soon