You can learn anything
There is this idea that we should only focus on one thing. I think that is true but most people interpret it in a different way. I think focusing on one thing is a great way to learn. When we are not distracted by anything, we can easily absorb ideas, and knowledge. The more time we spend doing one thing, the more we can master it.
This doesn't mean we should only focus on doing one thing in our whole life. We are allowed to learn as much as we want and can. Focusing on on thing means you only focus on one thing at a time. If you want to learn how to code, study coding. Spend all of your active hours learning to code, and making projects. Nothing else. Once you get the hang of it, then learn another thing. You won't forget how to code because you have already mastered it.
The problem with most people is they want to learn and think that learning is just about finishing an online course. This is a common trap that people fall into. Learning is an active process. Watching an online course is a passive process. We need to engage ourself with what we learn in order for it to be ingrained in our being.