HTML5 and CSS3 is the foundation to making websites. It's what this site is run on. HTML, gives content structure and meaning by defining that content as, for example, headings, paragraphs, or images.
This includes, Python, NodeJS and other languages. The back-end is the code that runs on the server, that receives requests from the clients, and contains the logic to send the appropriate data back to the client.
Rust, is not something im completely done learning. In fact, you can never be done learning a coding language. I thought I should include it here still.
Java is a great All-In-One coding language. I took the UW CSE203X, CSE301, CSE302, CSE303. All of which are college-level courses.