This is the 9366th most frequent Russian word.
татьяна
"Татьяна" is a female given name in Russian.
In this sentence, 'Татьяной' is instrumental case showing that the meeting was with Tatiana.
Мы познакомились с Татьяной на вечеринке.
We met Tatiana at the party.
Here, 'Татьяне' demonstrates usage of the dative case to indicate the direction of the action, specifically who will receive the call.
Я позвоню Татьяне завтра утром.
I will call Tatiana tomorrow morning.
Here, 'Татьяна' is used as a proper noun, referring to a given name.