Hear from e Heard from: Como usar

Eu estsva estudando e vir essa explicaçao , e essa expressao e nao entendi
You receive a card, email, or text message from a friend.

You can say: hear from

I heard from John. He sent me a birthday card.
Dad hears from Ian every week. Ian sends emails to him.
You will hear from me tomorrow. I'll text you.
You can ask:

Have you heard from Victoria?
Has Ryan heard from his brother?