Breakdown of Мой друг изучает английский язык.
друг
friend
мой
my (мой, моя, моё) / mine
изучать
to study
язык
language
Questions & Answers about Мой друг изучает английский язык.
Why is английский not capitalized here?
In Russian, adjectives made from names of countries or nationalities, like английский (English) or русский (Russian), are not capitalized unless they are the first word of a sentence.
английский язык is the object of the sentence, so shouldn't its ending change?
You are right that it is the direct object and is in the accusative case. However, for masculine nouns that are inanimate (not alive), like язык, the accusative case looks exactly the same as the dictionary form. The adjective английский copies this behavior too.
What is the difference between изучает and учит?
Изучать (here as изучает) means to study a broad subject, like an academic course or a language. Учить is more about memorizing specific things, like vocabulary words or a poem, though in casual speech people sometimes use it for languages too.
Do I always have to use the word язык (language) when talking about studying English?
Not always. You can often drop язык and just say Мой друг изучает английский. However, including язык is very common and makes the sentence sound complete.