Toolbar icon

Hi, Just bought a dell inspiron 2 weeks ago. i have now noticed that on mt toolbar(bottom right hand corner) There is a small White square box with an "A" in it.

When i roll the mouse over it nothing comes up to say what it is and i can right or left click it(i can all the others and when i hoover the mouse over them it tells me what it is.)  Does anybody know what this is and how i could remove it?!

Thanks.