Plain English Meaning
An area around certain airports where radar controllers will, if you ask, help line you up with other arriving aircraft and keep traffic safely separated. Using the service is optional but recommended.
Full Definition
Areas surrounding certain airports where radar-based air traffic services are provided to participating pilots, including sequencing of arriving aircraft and separation between IFR traffic and participating VFR traffic. TRSAs are depicted on VFR sectional charts with solid black lines and altitude information for each segment. Pilot participation is voluntary but encouraged. TRSAs are not classified as Class B, C, D, or E airspace; they overlay existing controlled airspace, and the at the is typically .