This is the 664th most frequent Azerbaijani word.
bilməyən
"One who does not know" or "unaware."
Here, 'bilməyən' is used as a participle to describe a characteristic of someone - that they do not know how to read the book.
Mən bu kitabı oxumağı bilməyən birisinə öyrətdim.
I taught someone who doesn't know how to read this book.
'Bilməyən' is used here as a descriptor for 'adam', forming an attributive clause meaning 'the person who does not know'.
Bilməyən adam həmişə çox sual verir.
A person who does not know always asks many questions.
In this sentence, 'bilməyənlər' functions as a plural participle to describe a group of individuals 'those who do not know'.