느냐 말다

whether or not to do it

The verb is said twice — once plain with "-느냐", once with 말다 "not do" — giving "whether or not". It names the open question at issue: whether that meeting would actually happen, whether to drink the pickle juice, whether to keep riding this, whether you take on the challenge or not. It usually stands as a noun phrase with 에 따라, 를, or 가 hanging off it, and it belongs to talk about a decision still hanging in the air.