This is the 1905th most frequent Korean word.
꿈을
"꿈을" means "dream" (as an object).
Here, '꿈을' is used as the direct object of the verb '꾸다', which means 'to dream'.
저는 어릴 때부터 큰 꿈을 꾸었습니다.
I have dreamed big dreams since I was young.
In this sentence, '꿈을' is the object of '이루다', meaning 'to achieve or fulfill'.
그는 자신의 꿈을 이루기 위해 노력하고 있습니다.
He is working hard to achieve his dreams.
Here, '꿈을' is part of the phrase '꿈을 가지다', which means 'to have a dream'.