What is the meaning of -ung?

-ing; forms nouns from verbs, usually describing either an event in which an action is carried out, or the result of that action.

used to form nouns from verbs

alternative form of -ynge

forming demonyms of place names

forming derivatives of nouns with sense of ‘belonging to, son of’.

forming nouns from verbs, denoting verbal action or an instance of it; or denoting a substance involved in the verbal action

Source: wiktionary.org