The defender left Valencia for the Gunners last year.
Last Friday he made his debut for Spain in their friendly victory against Serbia.
Now he talks about the move and life in England.
"I had spent almost my entire life in Valencia and leaving what had been my home was not easy. But it was the right decision, Mosquera tells Europa Press.
"I feel very comfortable in London and have settled in faster than I thought. I knew that the Premier League is a physical league, and many had said that my playing style would suit there. When the chance came to take the next step and show what I can do, I think I took it."
At Arsenal, he trains daily with established centre-backs like Gabriel Magalhães and William Saliba, something he highlights as crucial.
"From day one they have supported me, given me advice and looked after me, like older siblings. I am very grateful. They are two of the best centre-backs in the world, and it is a pleasure to train with them and watch them play every week," he added.