ㄴ다는

the fact/idea that ~; that says ~

Takes a whole statement and attaches it to the noun that follows: 반대로 가야 된다는 거야 'the point is that we have to go the other way', 다이어트 한다는 허언 'the empty claim that I'm dieting'. Most often the noun is just 거/것, which turns the whole thing into 'the fact that…'. It is a squeezed-down form of -ㄴ다고 하는 'saying that', so it also covers reported speech. After a consonant stem it appears as 는다는, and with adjectives as 다는.

Register: neutral, very common in speech