Starting from the icon on the left and going right...
The Cog Icon:
The Cog Icon toggles the feed preferences you have chosen on and off if pressed once. If you press and hold the Feed Preferences icon it will bring up the preferences for you to change. This, in turn, adjusts what you see on the feed.
This location pin icon toggles showing you local, around you deals (When highlighted) and deals further afield, posted to your home hub and national posts (when shaded).
The loudspeaker toggles promotions on and off. If you want to only view Deals and competitions make sure this symbol is shaded. If you want to see everything that everyone can offer then keep this highlighted.
The Trophy Symbol toggles competitions on and off. When Highlighted you will see all competitions available to you. When shaded you won't see any competitions (but where's the fun in that?).