Huawei Ascend G7 - What's this thing called?

Hello.
Here's the picture: http://ift.tt/1JVMEvo
What's the "thing" encircled in red called?

The reason I'm asking is: I want to make that thing larger, so it's easier to press it.
Right now it's too small for my finger to press, I usually end up pressing other icons...

Huawei Ascend G7 - What's this thing called?

Huawei Ascend G7 - What's this thing called?