You have 2 softwares:

Arduino (micro processor):
Similar to old "C" language, sequential. Easy language, and the commands are something like:
digitalWrite(led_pin_1, HIGH); to turn on a LED
servo_move.write(value); to move a servo in degrees
It's easy, you just need to have the circuit working, the software will be easy

Android:
I had to program the Android software, but again it's easy, you can use any language, just need to pass a value/variable by blueetooth.
all you need is to send 1 byte, then the Arduino software receives that byte and then
If byte == "A" then do A
If byte == "B" then do B and so on..