This is the 514th most frequent Greek word.
τους
"Them" or "the" (depending on context).
The word 'τους' here is used as a possessive pronoun referring to 'their friends'.
Έδωσα τα κλειδιά στους φίλους τους.
I gave the keys to their friends.
The word 'τους' here is used as a personal pronoun referring to 'them' as the object of the verb 'saw'.
Τους είδα στον δρόμο σήμερα.
I saw them on the street today.
The word 'τους' here is a personal pronoun functioning as the object of the verb 'represent'.