I mean that if someone asks you questions about code, you can respond intelligently and "think on the fly" about the subject in question. For instance you haven't just memorized something like e.g. the big-O time to access a hash table, but you have reasoning behind it: you know how it works in a few cases, your knowledge about it comes from an understanding of the implementation, and you can extrapolate that knowledge to new cases or variations of the problem, etc. Maybe your knowledge ends at some point but you could keep going if you had to: like maybe you don't know how hash tables interact with page tables or CPU caches but if that starts to matter you would be able to understand it and keep going.
The same way of thinking applies to design patterns (single responsibility principle->but why, and when is it okay to break?) or to architectures (OOP / dependency management -> yes but why? can you make a version yourself? can you work around problems with it?) or to libraries (React components->what are they trying to do? how do you keep that contract simple?) or to languages (JS->what are the tradeoffs? what features do you need? how important is upgrading or polyfilling?) etc.
All beyond-basic intelligence takes this form: not memorization but having a working understanding of how something operates that you can use and apply to new situations and investigate and drill into and wieldy flexible. I would call that "fluency". To be conversationally fluent in a subject is not necessarily to be an expert but to be able to "think" in terms of the concepts, and usually it means you could become an expert if the situation demanded it.
The same way of thinking applies to design patterns (single responsibility principle->but why, and when is it okay to break?) or to architectures (OOP / dependency management -> yes but why? can you make a version yourself? can you work around problems with it?) or to libraries (React components->what are they trying to do? how do you keep that contract simple?) or to languages (JS->what are the tradeoffs? what features do you need? how important is upgrading or polyfilling?) etc.
All beyond-basic intelligence takes this form: not memorization but having a working understanding of how something operates that you can use and apply to new situations and investigate and drill into and wieldy flexible. I would call that "fluency". To be conversationally fluent in a subject is not necessarily to be an expert but to be able to "think" in terms of the concepts, and usually it means you could become an expert if the situation demanded it.