Clinical rotations refers to the hands-on training done prior to graduation with real patients.
Lots of variety, but will usually include a combination of:
On-site clinic where you'll see patients under direct supervision of faculty
Off-site clinics, still run by the school, but offering a unique experience (inner city, specialty clinic like low vision/vision therapy, etc)
Off-site clinics that contract with the school to provide patient encounters: military bases, Indian reservations, hospitals, LASIK centers, private practices, ophthalmology practices, etc.