What does knowing a language mean?
I am proficient in a couple, that I can write off the top of my head with little or no reference material. Python, javascript, and C.
Several more languages I used heavily in the past, but not in a long time. I would need to check syntax and library references as I write, but could put together something passable without difficulty. C++, Java, Perl, PHP, bash, Pascal.
Other languages I used for a couple months on a one-off project. ML, Snobol, Fortran, COBOL, basic.
Then there languages I played around with a bit, but never did anything substantial with. LISP, Ada, C#, Eiffel, Objective C, Smalltalk, D, Ruby. I know something about them - but not much.
And there are languages I've heard of. Maybe even seen a program or two in, but never studied or tried to write in myself. Swift, Rust, visual basic, Algol, Go, brainfuck, Erlang, TCL, Haskell. I know of these languages.
So what should my answer be? Which of these languages do I "know"?