"By" is usually a preposition, but it can also be a part, sometimes called a "separable suffix", of a compound verb, as in, "stand by", meaning to wait. (Some persons, who do not accept that English has compound verbs with separable suffixes, would call "by" in "stand by" an adverb.)
adverb
The part of speech that the word my is used as is an adjective.
A suffix changes a word's part of speech. For example, the word 'happy' is an adjective. But when you add a suffix, which is an ending, it can change the part of speech. Happily is an adverb. Happiness is a noun.
for
it depends what word it is it could be any part of speech depending on the sentence
The word power is a noun. The plural form is powers.
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.
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 part of speech for this particular word is a noun.
The word speech is a noun.
The word speech is a noun.
The word speech is a noun.
What "part of speech" is the word "said?"
A suffix changes a word's part of speech. For example, the word 'happy' is an adjective. But when you add a suffix, which is an ending, it can change the part of speech. Happily is an adverb. Happiness is a noun.