The word leaves is a plural noun. Leaves can also be a present tense verb.
Leave is a verb.
The word could've is a contraction. It is the contracted form of the words could and have.
To the Adams Family, it isn't customary to leave a tip for the waiter.
The part of speech for this particular word is a noun.
part of speech
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
The part of speech for "unfamiliar" is an adjective.
The part of speech of "came" is a verb.
The part of speech for "twirl" is a verb.
The part of speech for "explicit" is an adjective.