This is the 7191st most frequent Russian word.
васильевича
"Васильевича" is the patronymic form meaning "son of Vasily" in Russian.
Here 'Васильевича' is used to address someone informally by their patronymic name.
Добрый день, Васильевича!
Good afternoon, Vasilyevich!
In this sentence, 'Васильевича' functions as a possessive form indicating ownership of 'музыка'.
Мы услышали музыку Васильевича.
We listened to Vasilyevich's music.
Here, 'Васильевичу' is a dative case form of the patronymic used to indicate direction toward or reference.