을 듣고

listen to … and

→ 을
phrase Very common #1,419
listen to … and 을 marks the object of 듣다, “to listen to” or “to hear”; -고 connects it to what happens next. The particle changes to 를 after a vowel-ending noun.
KO: 음악을 듣고 공부했어요.
EN: I listened to music and studied.