I have the Blue Yeti Pro, and love it.
The button is for muting.
Below that is a volume control. This knob turns continuously, so no stop at low or high end, but it is for USB volume, so apparently, the DAW should remember your setting.
On the other side are two knobs: Top is gain, this does stop at min and max.
Below that is pickup pattern. From left to right,it should be: Stereo, Omni, Cardioid, and Figure 8.
On the bottom are headphone, mini USB, and analog mic jacks. If yours is not the Pro, it would not have the analog.
P.S. Bear in mind that the Yeti is a side-address mic. This means that sound is picked up off the side of the mic, not off the end. You can tell where the mic's axis by feeling for the logo on the side. The diaphragm is directly above that...