उन

In a sentence

• मैंने उन किताबों को पढ़ा है।

  I have read those books.

  Here, 'उन' is used as a pronoun to refer to objects (books) that are previously mentioned or identified.

• उन छात्रों ने अपनी परियोजना पूरी की।

  Those students have completed their project.

  In this sentence, 'उन' acts as a demonstrative pronoun referring to specific students.

• आप उन सवालों के उत्तर क्यों नहीं दे सके?

  Why couldn't you answer those questions?

  Here, 'उन' is a pronoun referring to particular questions being discussed.