This is the 1966th most frequent Turkish word.
oldukları
"Oldukları" means "that they are" or "that they were" in English, depending on the context.
Refers to the state of 'being' of 'them'.
Onların burada oldukları kesin.
It is certain that they are here.
Describes the location 'where' the books are.
Kitaplar, oldukları masanın üzerinde duruyor.
The books are on the table where they are.
Relates to attributes or conditions of 'students' in terms of 'success'.