Depending upon the context, it can be an adjective, pronoun, or noun.
As an adjective, it means "an indefinite large number."
As a pronoun, it is still actually an adjective, but the noun it describes is assumed.
Examples :
"Many are called, but few are chosen." (implying people)
"Hundreds of dogs are injured in accidents, and many die." (implying dogs)
The rare use as a noun is as a reference to a majority of a group, e.g. the many as opposed to the few or the one.
adjective
there is one part of speech in the word up.
The part of speech for this particular word is a noun.
The part of speech that the word my is used as is an adjective.
The word "garish" functions as one part of speech, specifically an adjective. It is used to describe something that is overly bright, flashy, or showy.
H is a letter, not a word. To be a part of speech, it needs to be a word.
The part of speech for the word civilian is English grammar.
The part of speech for the word diplomacy is a noun.
The word speech is a noun.
The word period has 1 part of speech,a noun,but the word has 3 different meanings as a noun.
The part of speech for this particular word is a noun.
The word speech is a noun.
The word speech is a noun.