Professional supervision involves regularly-scheduled meetings with a trained supervisor. The supervisor is someone who has developed their own professional skills so they can guide others.

Supervision sessions happen at scheduled intervals. For instance every month, or every two or three months, or more. The pacing depends on how much guidance the supervisee prefers, and can be adjusted as needed.
In a supervision session, discussion focuses on reviewing work-related issues, and receiving feedback on how to resolve problems, develop new skills, and evaluate ideas. The scope of supervision is fairly wide. The focus of each session depends on the supervisee and their professional goals.
The relationship between a supervisee and their supervisor is separate from work, and sessions happen outside of the workplace. Anything that happens in a supervision session is confidential.