This is the 4291st most frequent Russian word.
английском
"English" (prepositional case, used with prepositions).
In this sentence, 'на английском' implies the language in which the books are written, specifying the mode of communication.
Я учусь читать книги на английском.
I am learning to read books in English.
Here, 'английском' serves as part of the phrase describing the specific language being discussed, 'English language'.
На уроке мы говорили об английском языке.
During the lesson, we talked about the English language.
In this context, 'на английском' indicates the language context in which grammar is being studied, emphasizing practical usage.