Mentor Sessions are asynchronous sessions that happen on the GitLab Community Discord to help move merge requests forward. They are intended to help merge requests having difficulty getting ready for review.
@Contributor Success, optionally together with your thoughts and questions
Mentoring sessions are useful to clear out your thoughts or discuss how to move forward. Everyone is different, so these sessions are to cater to the different needs. They happen async and in Discord because then everybody can contribute to the conversations and others can learn as well.