Ask HN: How to know what I don't know, early in my career

As the end of the year approaches I took time to reflect. I couldn't finish all that I planned. Therefore I need to prioritize going forward. Somethings are easy to argue for. I.e. look at used techstacks and how they work together (React, FastAPI, sqlalchemy).

Now my question: With experience, what do you think is important as a software developer. What is something that juniors are often not aware off. Something they don't know they don't know?