niebieskich

In a sentence

• Widzę niebieskich ptaków na drzewie.

  I see blue birds on the tree.

  In this sentence, 'niebieskich' is the plural genitive masculine or animate use, qualifying 'ptaków' (birds).

• Kupuję kwiaty o niebieskich płatkach.

  I am buying flowers with blue petals.

  Here, 'niebieskich' describes 'płatkach' (petals), using the plural locative masculine or neuter form.

• Mówię o tych niebieskich.

  I am talking about those blue ones.

  In this case, 'niebieskich' stands alone as an adjectival noun referring back to a previously mentioned group.