The purpose of this method, whose name may or may not have been invented by the homonymous American company, is to highlight the lessons learnt and possibilities that arise from a meeting, training session, project or even a short encounter.
Depending on how much time you have, you can ask the group to share their thoughts in pairs before sharing with the whole group.
You can also skip the sharing stage and use this time as individual introspective time.
Or, depending on the scenario, you could take the sharing part further and turn it into a reflection on what actions need to be implemented going forward.