NAKANAKA + VERB in NEGATIVE FORM なかなか～ない Grammar N4-15

Nakanaka" followed by a verb in negative form expresses that the speaker has already made an effort to do something, but cannot seem to be able to do it or it takes a lot of effort, or takes a lot of time to be able to do it, much more than expected.

The translation is "not easy to do", "be struggling to do", "not able to~".
In this video, we'll see in detail how this expression works and how to build it into your conversations.