Plain English Meaning
Two aircraft fly approaches to two parallel runways at the same time, on separate approach paths, without ATC keeping a fixed distance between them. A controller watches each path closely and a protected strip of airspace sits between them so the aircraft stay safely apart.
Full Definition
An ATC procedure permitting simultaneous instrument approaches to parallel runways whose centerlines are separated by at least 3,000 feet (or less where authorized), conducted with no required radar separation between aircraft on adjacent final approach courses. Each approach is monitored by a dedicated final monitor controller, and a No Transgression Zone (NTZ) is established between the final approach courses to ensure safe .