sínu

In a sentence

• Hann færði sínu barni gjöf.

  He gave his child a gift.

  Here, 'sínu' is used to denote possession in relation to the subject ('Hann'), indicating that the child belongs to him.

• Hún bað um að hafa tíma með sínu fólki.

  She asked to have time with her people.

  In this sentence, 'sínu' refers back to 'Hún' to indicate that the people are related to her in some way, showing a possessive relationship.

• Við verðum að gera þetta á okkar eigin forsendum og að líta eftir okkar eigin málum á okkar eigin hátt, frekar en á sínum.

  We have to do this on our own terms and look after our own affairs in our own way, rather than on theirs.

  Here, 'sínum' (the masculine plural dative form) refers to another group not including the subject, contrasting whose terms are being considered.