The phrase "large lockers" refers to storage spaces that are bigger than regular lockers. They are used to keep bigger items or more belongings. Full definition
The new bathhouse provides larger locker rooms, two separate family dressing rooms, and an expanded concession area that serves both pool users and general park users. (ahpd.org)
There are also large lockers for each bed, with the lock included, which is nice for us having been robbed at a hostel before when our lock did not fit the lockers. (traveltoblank.com)
This modern hostel has clean bunks with large lockers and an awesome common area where you can socialize and meet other travelers. (adventureinyou.com)