Accelerometer Sensor app helps you to see and record the data that accelerometer Sensor gives
It's gives you X accel Y accel and Z accel
Which is values recorded by accelerometer sensor app
(rate of change of velocity).
For example, an accelerometer at rest on the surface of the Earth will measure an acceleration due to Earth's gravity, straight upwards (by definition) of g ≈ 9.81 m/s2. By contrast, accelerometers in free fall (falling toward the center of the Earth at a rate of about 9.81 m/s2) will measure zero
You can use this app for study and experiment purpose

added: now you can use this app as Accelerometer Sensor checker to find out if your device has Accelerometer Sensor

This app using your device built-in accelerometer sensor and shows your the X accel value, the Y accel value and the Z accel.