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.
One part.
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.