을/를
object particle
Meaning
을/를 marks the object: the thing the verb acts on.
Form
After a consonant
을
음악 → 음악을
After a vowel
를
커피 → 커피를
Examples
밥을 먹어요.
I eat a meal.
음악을 들어요.
I listen to music.
한국어를 공부해요.
I study Korean.
Watch out
Often dropped in speech
In casual speech people often omit 을/를. The particle is still what tells you the object. Learn it, then you will hear when it is left out.