Learn Hardcore Russian: Я пишу письмо, пока слушаю музыку. - I am writing a letter while listening to music.

Here пока means while, introducing a temporal clause that shows two actions happening at the same time. It’s not the same as пока meaning “bye” or “until” in other contexts.

Why is there a comma before пока?

Because пока is the conjunction that starts a subordinate clause of time. In Russian, you separate the main clause from a subordinate temporal clause (introduced by когда, пока, etc.) with a comma.

Both пишу and слушаю are in the present tense. How do I know if they mean “I write/listen” or “I am writing/listening”?

Russian doesn’t distinguish simple present from continuous with different forms. The present tense of an imperfective verb (like писать → пишу, слушать → слушаю) can mean either “I write” or “I am writing,” depending on context. Here the context of simultaneous actions signals “I am writing…while listening.”

Why didn’t we use the verbal adverb слушая музыку instead of пока слушаю музыку?

You could say “Я пишу письмо, слушая музыку.” That uses the verbal adverb (деепричастие) слушая and is perfectly correct. Using пока + finite verb simply gives equal weight to both actions, whereas the verbal adverb sometimes makes the second action feel more like background.

Can I drop the pronoun я in both clauses?

Yes. Russian is a pro-drop language, so verb endings already show the subject. You can say “Пишу письмо, пока слушаю музыку” without any loss of meaning, unless you want to add emphasis.

Could I swap the order of the clauses?

Absolutely. You can say “Пока слушаю музыку, я пишу письмо” or even “Пока слушаю музыку, пишу письмо.” The meaning stays the same, though placing the temporal clause first can slightly shift the emphasis.

Why is письмо unchanged in the accusative, but музыку changes from музыка?

письмо is a neuter noun; in the singular accusative it looks just like the nominative (письмо → письмо).
музыка is feminine; in the singular accusative it changes -а to -у, so музыка → музыку.

Why is there no conjunction и between пишу and слушаю?

These aren’t two independent verbs in a simple list, but rather a main clause plus a subordinate temporal clause introduced by пока. The conjunction и (and) would be used for coordinate verbs or clauses without a temporal link, e.g. “Я пишу письмо и слушаю музыку,” which simply lists two actions without implying “while.”