-을 줄 알다

V/adj/이다, 아니다 + ㄹ/을 줄 알다(모르다) 1. This indicates the ability or method to do something. (I know how to~)

토니 씨는 한국 음식을 만들 줄 알아요?

Does Tony know how to make Korean food?

태형 씨는 운전 할 줄 몰라서 지하철만 타요.

Taehyung only takes the subway because he doesn't know how to drive.

치히로 씨, 삼겹살은 쌈을 싸서 먹어야지. 먹을 줄 모르네.

Chihiro, you gotta wrap the samgyeopsal in lettuce. You don't know how to eat. (joke nuance)

• ~을 수 있다(can) vs ~을 줄 알다(know how to~)

~을 수 있다	~을 줄 알다
It indicates the possibility and ability. 저는 운전할 수 있어요. → I can drive.	It indicates that someone knows how to do it or the method. 저는 운전할 줄 알아요. → I know how to drive.

V/adj/이다, 아니다 + ㄹ/을 줄 알다(모르다) 2. This indicates the knowledge of a fact or state. (I knew it would~/ I didn’t know it would~) It is typically used with the verb in past tense; 알았다 and 몰랐다.

식당이 빨리 문을 닫을 줄 몰랐어요.

I didn't know the restaurant would close early. (but it’s actually closed early.)

태형 씨가 노래를 잘 할 줄 몰랐어요.

I didn't know that Taehyung could sing so well. (but Taehyung actually sings well.)

수지 씨가 그 사람과 결혼할 줄 알았어요.

I knew that Suzy would marry that person. (it can mean both ‘she actually married him’ or ‘she didn’t’. The sentence itself doesn’t tell us, the meaning depends on the context.)

• You can change the noun modifier part depending on what you want to convey.

식당이 문 닫은 줄 몰랐어요.

I didn't know the restaurant had closed.

식당이 문 닫는 줄 몰랐어요.

I didn't know the restaurant is closing.