This is the 3222nd most frequent Korean word.
과자를
"과자를" means "snack" or "cookie" in the accusative form in Korean.
Refers to snacks being eaten, direct object of action '먹고 있다'.
나는 과자를 먹고 있어요.
I am eating snacks.
Refers to snacks as an object of preference in the sentence.
그는 과자를 좋아해요.
He likes snacks.
Refers to snacks that were purchased and given, object of '사 주다' action.