Hughes believes the Spain under-21 defender, who can also play at centre-half or as a defensive midfielder, will prove to be a wise long-term investment.
He said: "Marc is a young man who has made a big step. He has come from one of the top clubs in the world to try to make his career in the Premier League.
"It is a big decision, but I have been impressed with him. I think we have a very good player on our hands.
"His technical ability is without question, he just needs now to adjust to the Premier League."