Plain English Meaning
When ATC has the time and the radar information to help, controllers can tell pilots where the bad weather is and suggest a way around it. The pilot still decides whether to take that suggestion and is still in charge of flying the airplane safely.
Full Definition
A service in which Air Traffic Control, workload permitting, provides pilots with information about observed precipitation and thunderstorm activity, and may suggest headings or routes to help the pilot avoid hazardous weather. The pilot remains responsible for the final decision to deviate and for the safe operation of the aircraft.
Context Anchor
Seen in instrument flying when a needs help avoiding , precipitation, or other unsafe weather while already .