Facebook introducing announcements to groups will give admins the flexibility to specify Group rules, Special offers, Upcoming events, etc. It was always a problem to cramp all the information into one single pinned post that most members didn't even read. That problem is solved. Thank you, Zuck!
I recommend reading this article for more details: https://www.socialmediahound.com/2018/02/23/how-to-use-facebook-group-announcements/
Note: Facebook has not made this feature available for all groups yet.
