Programming languages aren't very hierarchical - once you learn Python, even if you learn other languages later, you'll still find uses for Python.
Just because Python is easy to learn (which is why it's recommended as a good language to start off with) doesn't mean it's weak or otherwise hindered.
Python is used in games, small and large. It's used for the backends of websites. It's used as a programming language, and as a scripting language.
But that didn't really answer your question.
What do you learn after Python? Well, after sticking with Python for two or three years (which is what I recommend), the landscape of what is in style, and what people recommend, what is new, and what is stable and mature, may have changed.
After you learn Python, you'll either already have picked up what to learn next, or else you'll be better equipped to ask here or elsewhere for suggestions.
Maybe C#. Maybe C++. Maybe something entirely different. But even 10 years from now you'll still use Python in addition to whatever else you learn - whatever tool is best suited for whatever project you are undertaking at that distant point in time.