How do you know if you know a programming language?

Question

IT education

Hello.
I've been learning python for a while.
I read the book "Python Bite" and "Charles Petzold's Code", did not finish reading the book "Groking Algorithms", while solving the Euler project in parallel.
I heard that people have been learning programming languages ​​for several years and I don’t understand what exactly they are learning. That is, a good knowledge of the language is the knowledge of a heap of libraries? And the main question: how much do you need to know to go to work? Now I'm 16 and I have a lot of free time, and I don't know in which direction to continue learning the language. Is it possible to learn only by solving problems from the Euler project, or do you need to read something else for this?
Or is it already possible to start learning the next language? I want to either understand assembler further or learn c / c ++.
What do you think about this?
Thank you in advance.

Answer 1

You have not learned the language. Just read about it.
Start writing a program. What - think for yourself. The more difficult the better
You can come up with and write a bot for TG for example. Let's say that will upload all the posts from the insta to the group. Well, the ability to specify the bot from which page you want to get the unloading

Answer 2

"I learned English from a textbook, I speak with a dictionary, I'm afraid of people.
When can I start learning Chinese?"