It really does depend on how you use it, but most of the time it is an abstract noun: 'It could have been anything'
No part of grammar
Spelling is not officially a part of grammar.
The word "grammar" is a noun.
"Not" is typically classified as an adverb in grammar, as it is used to modify verbs, adjectives, or other adverbs by expressing negation or denial.
Grammar
connectives
"Of" is a preposition.
linking verb
linking verb
"These" is a demonstrative pronoun that is used to point out specific items or people that are nearby in space or time. It is also used as a determiner to indicate a specific group of things.
I is watch monitor.
The correct grammar is "You didn't have to send us anything." Using "nothing" is a double negative and is considered grammatically incorrect.