This is the 10186th most frequent Russian word.
библиотеке
The word "библиотеке" means "library" (prepositional case) in English.
The word 'библиотеке' is in the prepositional case, showing location ('in the library').
Я был в библиотеке вчера.
I was in the library yesterday.
The word 'библиотеку' is in the accusative case, expressing direction towards ('to the library').
После уроков мы пошли в библиотеку.
After classes, we went to the library.
The word 'библиотеке' is again in the prepositional case, used to refer to a location ('in the library').