Fires is a noun (plural form of fire) and a verb (third person singular conjugation of fire).
It is an adverb.
The word "incendiary" can be both an adjective and a noun. As an adjective, it describes something capable of causing fires or provoking violence. As a noun, it refers to a person who deliberately starts fires or stirs up conflict.
The part of speech for this particular word is a noun.
part of speech
The part of speech for "answer" is a noun.
what part of speech is beneath
adverb
The part of speech for "explicit" is an adjective.
The part of speech for "lecturer" is a noun.
The part of speech for "rapid" is an adjective.
The part of speech of "came" is a verb.
The part of speech for "breezy" is an adjective.