This is the 2367th most frequent Russian word.
обоих
"Both" (genitive or accusative masculine/neuter form).
'обоих' functions in the prepositional case, used with 'о' to mean 'about both' when referring to masculine or animate plural nouns.
Она говорила обоих с уважением.
She spoke about both with respect.
'обоих' here means 'both' and is in the genitive case to agree with 'друзей', the object.
Я видел обоих друзей вчера.
I saw both friends yesterday.
'обоих' is used as a masculine/animate plural pronoun in the accusative case, matching the implied object 'both people'.