System admins can mark Knowledge items as 'mandatory read' by certain groups of people.
If there are items that you need to read, a notice will appear on the Knowledge section and on your Dashboard that reads 'You have items that you are required to read'.
To view a list of these items press See all mandatory read items.
To mark an item as read, go to the item and press the Mark as Read button that appears at both the start and the end of the item. It will now be removed from your mandatory read list.