The 28-year-old, who was frozen out at Athletic Bilbao last season after declaring his intention to leave the club, feels that learning Italian before arriving in the country has helped him to settle at the club.
"I have already made friends with everyone in the locker room," he told reporters. "For me it was very important to learn Italian before getting here.
"I'm glad I made the effort to learn – I already feel like a part of this group."
The Spanish international joined the Bianconeri on a free transfer this summer.