This is the 9358th most frequent Russian word.
таня
"Таня" is a diminutive form of the Russian female name "Татьяна" (Tatyana).
Here, 'Таня' is used as a proper noun, referring to a person's name, representing the subject of the sentence.
Таня рисует картину.
Tanya is painting a picture.
In this sentence, 'Тане' is the dative case form of 'Таня,' denoting the indirect object of the action—to whom the call will be made.
Она позвонит Тане завтра.
She will call Tanya tomorrow.
Again, 'Тане' is in the dative case, showing possession or relation in this sentence structure.