This is the 1157th most frequent Turkish word.
milletin
"Milletin" means "of the nation" or "the nation's" in English.
Here, 'milletin' refers to 'of the nation' indicating possession or relationship with the collective term 'millet' (nation).
Milletin geleceği için çalışmak hepimizin görevidir.
Working for the future of the nation is everyone's duty.
In this sentence, 'milletin' again means 'of the nation,' specifying the source or subject of the history.
O, milletin tarihine dair birçok kitap yazmıştır.
He has written many books about the history of the nation.
Here, 'milletin' is used to indicate what is being enriched, showing the possessive aspect in relation to 'millet'.