This is the 9423rd most frequent Turkish word.
adaların
"Adaların" means "of the islands" or "the islands'".
The word 'adaların' is the genitive form of 'ada', meaning 'of the islands', indicating possession.
Adaların tarihini araştırıyorum.
I am researching the history of the islands.
Here, 'adaların' is used in the genitive form to specify that the beauties belong to the islands.
Bu belgeselde adaların doğal güzellikleri anlatılıyor.
The natural beauties of the islands are described in this documentary.
In this sentence, 'adaların' specifies a scope for 'hepsini' (all of them), linking the concept to the islands.