Hide/unhide on task bar

I hope this is the right forum for this question. On the bottom right of my screen where the clock is, there are several icons. However, at the left side there are 2 arrow heads pointing towards the icons. When I put the mouse on them, it says  "Unhide". If I click, it moves the hidden icons into view. It then hides them again. How can I get rid of this, for me, very irrritating thing? I did not knowingly put it in. Please help this newbie with this problem. Thanks!!!!