좋을까

would be good

→ 좋다
좋 feel pleasant + 을 Future attributive + 까 Wondering or deliberative question ending
adjective Uncommon #11,880
would be good Used when wondering or asking what would be a good choice.
KO: 오늘은 뭐가 좋을까?
EN: What would be good today?
Forms of 좋다

우리 엄마 기분이 왜 안 좋을까?

I wonder why my mom is in a bad mood.

— Wonderland (2024)

우리 딸, 왜 기분이 안 좋을까?

Why is my daughter in a bad mood?

— Wonderland (2024)

어떤 메뉴가 좋을까?

What menu would be good?

— 미스터 헐리웃 (2000)

뭐라 말하면 좋을까

What should I say?

— 날씨의 아이 (2019)

뭐가 좋을까?

What would be good?

— 어느 가족 (2018)

좋아, 누가 좋을까?

Okay, who would be good?

— 롤라 런 (1998)

너희들은 뭐가 좋을까?

What do you guys like?

— 센과 치히로의 행방불명 (2001)