In the sentence, the word <em>whose</em> is a relative pronoun, and it indicates possession. The man whose car I borrowed ( <em>The car that I borrowed belongs to the man/ I borrowed the man's car.) We use </em><em>whose</em><em> to introduce a relative </em>clause that indicates possession by people, animals and things. Another example is: T<em>he film is about a spy whose wife betrays him.</em>