How do I view Serial Output on an Android Device?
These steps will allow your Android device to function as an Arduino Terminal. 


Download a Serial Terminal app.  I'm using Android Hyperterminal, English version.
Attach an OTG ("On The Go") cable to your Android device.
Attach your Arduino to the OTG using your regular USB cable.
Make sure the terminal program is set to the same baud rate as your sketch.
Run the terminal App and select the USB port.