'Their' usually functions in sentences substantially as an adjective, but technically, "their" is the possessive case of the third person plural personal pronoun. All possessive case nouns and pronouns usually function in a sentence as adjectives, but, since the parts of speech are usually considered mutually exclusive for a single word in a single sentence, it may be important to retain the distinction.
Adjective
A part of speech of their is Adjective
Noun
PRONOUN
what part of speech is work
adverb
i want to know what part of speech is camping
what part of speech is beneath
what part of speech is eleven
part of speech
The part of speech for this particular word is a noun.
adverb
what part of speech is work
what part of speech is beneath
Adjective
The word speech is a noun.
Yes, conjunction is a part of speech.
What part of speech is thaw
i want to know what part of speech is camping
what part of speech is beneath
The part of speech for "archaeologist" is a noun.