These are End Users with the "Featured" system (standard/default) field toggled on. Marking an End User as a "featured" can be done manually (e.g. when viewing a table of End Users), or when you're importing End Users with the import template.

Marking an End User as featured can help you to determine who is important to reach out to or get in contact with when there is something happening with the Company's account, or the time for renewal is up.

There is also the Relevancy Score to help you do this, but sometimes the decision makers aren't ones that log in all of the time or that you're having a lot of emails or chats with so they will score a "Low" in relevancy. But they are the ones that will be important to reach out to and make sure everything is all set before renewal time.