As you might know, a Selection can be opened and viewed by multiple users at the same time. If this happens, different users can add parallel changes that will lead to incongruous results.
In this case, DESelect Segment allows you to see who are the users on the same Selection as you are to prevent this from happening and make sure you properly align.
When multiple users are in the same Selection, DESelect Segment displays a real-time banner, with the number of users who are in that Selection at that moment.
Once you click on the Users icon, you will know who are those users.
Important Note: In case there are some modifications from different users who are using the Selection at the same time, the version saves or runs first will be considered the latest version. Keep in mind this might cause errors or discrepancies in the results.