The faun decides to make a friendly (by which we mean "fairly creepy") visit to Ofelia's room.
He gives her a mandrake root to place under her mother's bed in a bowl of fresh milk. She's supposed to give it two drops of blood each day and it will…help her mother? The faun isn't really clear about that part.
Then he tells her of her second task. She is going to a very dangerous place with an inhuman thing and a sumptuous feast she must not eat.