His teachers are not happy with his progress. They think he … too much time playing his guitar and reading music magazines.

His teachers are not happy with his progress. They think he is spending too much time playing his guitar and reading music magazines.

Перевод: Учителя не довольны его  успехами. Они думают,  что он  проводит  слишком много времени, играя на гитаре и читая музыкальные журналы.