Many English words ending in "ing" are forms of verbs. (See -ing for the distinct Old English origins of the suffix.) They are known as gerunds, present participles, gerundial nouns, or verbal nouns. {{present participle of}} is the template used to "define" and categorize such words. It is used under the Verb PoS header.
They are used in various ways, as nouns, adjectives, and to form progressive aspect verb forms.
When being used as nouns, the generic meanings are "the practice or activity of engaging in the activity or process referred to by the verb", generally uncountable, and "an instance of such practice or activity", countable. The countable sense can usually be found in the plural. As a result there is virtually no convenient grammatical test available to determine when it is necessary to have a Noun PoS section in the entry for such words.
There are -ing forms that have meanings that do not obviously fit these generic senses. In such cases it is necessary to have a noun section of the entry that reflects these specific senses.
Discussion about -ing forms in Beer parlour or elsewhere: