ㄴ데 맞다

and that's right

"-(으)ㄴ데" lays down background before the main point, and 맞다 is "be correct, that's right". Together they soften an agreement or a check: it's like a root, and yes, this is it; that's very important, right; sorry, but that's correct, isn't it? The -데 is what keeps it from sounding blunt. One line uses the other 맞다, the one meaning "get hit" — a caption about someone taking hits during the other team's attack.

Register: conversational