During the interview, when asked if he had any experience teaching English, Kevin couldn't get his head around the skills needed for the job in Japan. How does this "can't get my head around it" work?

面接で、英語を教えた経験があるか聞かれたケビンは日本で仕事に必要なスキルのことまで頭が回っていませんでした。この「頭が回らない」はどうやって使うのでしょう？