This is the 342nd most frequent Japanese word.
なかなか
"なかなか" means "quite," "considerably," or "not easily" (often context-dependent).
Here, 'なかなか' is used to mean 'rather' or 'quite' to indicate that the level of difficulty is notable.
この宿題はなかなか難しいですね。
This homework is rather difficult.
Here, 'なかなか' makes an affirmative statement to express that something is considerably or surprisingly good.
なかなかいい出来ですね。
It turned out quite well.
In this context, 'なかなか' is used with a negative verb to mean 'seldom' or 'not easily'.