It means refreshing or processing. Try Settings, Storage, Cached Data, and clear the cache. Then Power Off and Restart the phone.

What do the arrows on my phone mean?

Two rectangles with arrows in them

This symbol shows that Android Beam is turned on. This works with NFC to transfer files from one Android phone to another wirelessly and quickly. It can be turned off in the ‘Wireless & Networks’ settings menu.

What are the arrows at the top of my Samsung Galaxy?

The arrow with a line underneath it is the download icon. It will appear when your phone is downloading an update, an application, or a file. Once the file is done downloading, the icon will be fully white; to remove the icon, swipe down from the top of your screen and swipe each notification away.