The star symbol is a way to make a task or note something you can come back to in the future.
It bookmarks the post so you can attend to it later.
Under any task or note, simply click on the three dots to expand the menu.
You can find all starred posts under your profile, called My Starred. These will display on the left menu of your screen, right below your profile name.
Once you are done reviewing something that needed your attention, you can remove the star from the message and it will remove it from your bookmark list.
If a message is not starred, the icon will show blank.
If the message is starred, the icon will show filled in (or black).
