I suggest you start with JavaScript. It’s very popular for web development and can build on what you know. From there you could pivot to python because it’s a great tool to use advanced libraries without having a ton of deep knowledge or to C to learn more about how the computer works and memory mgmt.

There are a ton of popular JavaScript web development frameworks you could try. Angular and react are both quite popular.

Personally, I use a lot of .net which can do web development and a ton of other stuff. I really like how approachable their documentation is and how many libraries there are for it, but I’m not sure I’d recommend it as a great learning tool. C# is a pretty slick object oriented programming language, but you might be better served learning that in other platforms.

You might also want to start looking into architecture and algorithms too. Leetcodes are a great way to learn algorithms, but expect to have to look stuff up. You’re not going to intuit a sliding window function. For architecture I’d start with design patterns. That’ll explain how to design entire large programs and why you do things. Specifically, the book Design Patterns: Elements of Reusable Object-Oriented Software