also: なになのか
what is it (that); the meaning of something; what something is about
Used to ask for the essence, meaning, or true nature of something. Often implies a deeper inquiry beyond surface description.
I sometimes wonder what life is all about.
I couldn't understand what he really meant.
Alternate reading なになのか is also used, but less common than なんなのか.
Combination of 何 (what) + な (attributive form of copula だ) + の (explanatory/emotive particle) + か (question marker). The reading なんなのか is a contraction of なになのか.