This simple application supports the real time visualization of all sensors of your phone in form of a line graph. It is therefore also useful to find out which sensors are built in in your device. A legend describes what kind of data the values represent.

In the case of an accelerometer, the read out data will be acceleration x-axis, y-axis and z-axis (in this order) and the unit m/s^2.

To get more information about the description and units of the sensor data check out: https://developer.android.com/reference/android/hardware/SensorEvent.html
Be aware that the app doesn't feature the recording of sensor data.

This application is open source!
https://github.com/michaeltroger/sensor-visualization/