않다는

that ... is not, that ... does not

→ 않다
않 not (forms a negation after -지) + 다 Plain declarative ending + 는 present attributive ending
verb Rare #29,611
that ... is not, that ... does not Follows a negated predicate to introduce a clause meaning “that ... is not/does not.”
KO: 그게 쉽지 않다는 걸 알아요.
EN: I know that it isn’t easy.
Conjugation of 않다
Indicative
않다는

문제는 우리는 시간이 충분하지 않다는 것 이다.

The problem is that we don't have enough time.

당신 문제는 돈이 충분치 않다는 건 가요?

Is your problem that you don't have enough money?

— 달콤한 인생 (1960)