This is the 9968th most frequent Russian word.
английcком
The word "английском" means "English" in the prepositional case, typically referring to "in English."
'На английском' here expresses the language used during the conversation in the lesson.
На уроке мы разговаривали на английском.
In the lesson, we spoke in English.
The phrase 'на английском' specifies the language being used to write the essay.
Она пишет эссе на английском.
She is writing an essay in English.
Here, 'на английском' indicates the language in which the book is written and being read.