nguh-beng-gun
or in IPA [ˈŋaʔbeŋgan]

Remember that the 'h' is a glottal stop (a sudden stop in the flow of air) and has no similarity to how it is pronunced in English. You can leave the glottal stop out> ngabengkan.

nga-h-beng-ka-n
The nga- is the first person pronoun prefix 'I', the 'h' glottal stop indicates immediacy (right now) and the verb stem is -bengkan which in turn is made up of the stem -beng (as in the noun kun-beng 'cognition, thought process') and the verb theme -kan which on its own means 'to take'. The final -n on -bengkan marks the non-past tense (i.e. present and future).

-bengkan = non-past tenses (know, think)
-bengkang = past tense (thought, knew)
-bengkani = past imperfective (were thinking, used to think about)
-bengkayi (irrealis/negative, should think/know, didn't think)

Remember that you can substitute any of the pronoun prefixes on the verb stem:
yi-bengkan
ka-bengkan
ngurri-bengkan
karri-bengkan etc

Note also, that the synonym -burrbun is more common in Gunbalanya Kunwinjku and -bengkan is more common in Maningrida Kuninjku and Kune. Both are used in Gundjeihmi.

Med, nga-djalbengkan.
Hang on, let me just have a think about this.

Wurdurd minj kabirri-bengkan.
Children don't understand.

Bedberre man-me.
Yoh, ngahbengkan.

That is their food.
Yes, I know.

Ngudda ngurri-bengkayi!
You all, you should know!