This is the 11743rd most frequent Turkish word.
geldikleri
"Their arrival" or "that they came."
In this sentence, 'geldikleri' means 'they arrived,' used within an indirect question clause ('ne zaman geldikleri'), making it function as the subject of the sentence.
Onların ne zaman geldikleri belli değil.
It is not clear when they arrived.
Here, 'geldikleri' translates to 'they arrived,' derived from the verb 'gelmek' (to come) and the relative clause structure, indicating an attributive clause describing the place (yer).
Geldikleri yer çok güzeldi.
The place they arrived was very beautiful.
Here, 'geldikleri' refers to 'their arrival,' employing a nominalized form from the verb 'gelmek' (to come) used with a possessive pronoun implied in Turkish syntax.