You sit down and don't know what to code on. To be able to answer what you should work on, we must take a look at your motivations. Why do you want to code? Is it because you want to get skills to be able to get a certain type of job? Is it because you have an idea you want to realize? Or something completely different?
When you have formulated why, you have to define a path how to get there. What subtasks do you have to complete? What do you have to learn? What do you have to create?
After doing this little exercise, things might become a bit more clear what you should work on.
Hope this was helpful. Don't hesitate to ask if you have some questions :)