One of the ways of finding out the current volume level of your device is to press the volume buttons on the side of your device. VolumeStatus 2 is a brand new jailbreak tweak that allows you to quickly determine the current volume level of your device directly from the Status Bar.
The tweak adds a volume indicator to the Status Bar that allows you to take a quick peek at the volume level without pressing the volume buttons. The tweak doesn't display the exact volume level, but it gives you an idea of how much the volume is. The icon is followed by curved lines indicating the device's volume level.