This is the 664th most frequent Serbian word.
многи
"Многи" means "many" in English.
The word "многи" is used as a pronoun describing a quantity, referring to "many people" here.
Многи људи воле сунчане дане.
Many people love sunny days.
The word "многе" is an adjective agreeing with the noun "разлоге" in gender, number, and case.
Имао сам многе разлоге да донесем ту одлуку.
I had many reasons to make that decision.
Here, "многи" is used as a pronoun in its plural form, implying "many individuals" to conform to the context of attendance.