Noun that refers to relationships, ideas, qualities, theories, feelings, states of being, etc are called abstract nouns.
A pronoun is a word used in place of noun.
The words that describe noun are called describing words or adjectives.
‘Shoal or School’ is the collective noun of fish. (‘शोल’ मछली की सामूहिक संज्ञा है।)
‘Fleet’ is the Collective Noun of Ships (‘बेड़ा’ जहाजों के लिए सामूहिक संज्ञा है।)
A countable noun has both a singular and a plural form, and it names anything (or anyone) that one can count.