약점이 · 약점을
weakness, weak point
Example
누구에게나 숨기고 싶은 약점이 하나쯤은 있어요.
Everyone has at least one weakness they want to hide.
Word parts
약 weak+점 point
Literally 'weak point'. -점 = point, feature: 장점, 단점, 강점.
Good to know
약점을 잡히다 means 'to have one's weak spot exploited' — someone has dirt on you.