Meaning of “mine” - Learner’s Dictionary

mine

pronoun us uk /maɪn/

A2 the things that belong or relate to the person who is speaking or writing:

I borrowed them from a friend of mine.
"Whose book is this?" "It's mine."
Can I use your pen? Mine's not working.

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(Definition of “mine pronoun” from the Cambridge Learner’s Dictionary © Cambridge University Press)