сибирской

In a sentence

• Я купил шапку из сибирской шерсти.

  I bought a hat made of Siberian wool.

  Here, "сибирской" functions as an adjective modifying "шерсти" (wool), describing its origin as from Siberia.

• На сибирской реке летом можно увидеть много птиц.

  On a Siberian river in summer, you can see many birds.

  In this case, "сибирской" modifies "реке" (river), specifying that the river is located in Siberia.

• Она гордится сибирской природой своего края.

  She is proud of the Siberian nature of her region.

  Here "сибирской" modifies "природой" (nature), emphasizing its characteristic as representative of Siberia.