The word 'fun' is a noun, a common, abstract, uncountable noun; a word for a concept.
Examples:
Noun: "The puppy is full of fun!" or "Join in the fun!"
Adjective: "The puppy is fun" or "The party decorations are fun"
Note: fun can also be used as a verb, as in joking or kidding, but this is less common than the other two forms in American English.
The part of speech that the word my is used as is an adjective.
Fun is an adjective in this sentence because it does not tell how was which was or where was.
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 part of speech that the word my is used as is an adjective.
The part of speech for this particular word is a noun.
Fun is an adjective in this sentence because it does not tell how was which was or where was.
The part of speech for the word diplomacy is a noun.
The part of speech for the word civilian is English grammar.
H is a letter, not a word. To be a part of speech, it needs to be a word.
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?"