Explaing tabs on attached pic of Arduino program

Please explain the tabs on this picture of Arduino program. I have only seen it create one tab, the name of the current program being ran.

The Sensor tab probably refers to another file in your project. If you open your project folder you should see a file named Sensors."some extension, pde, ino, c, h, what have you". This file is probably included in some way into your main project or part of another file. It is likely being used to control sensor data of some sort.