int k = kbValue(keyboardValue);
in plain English: kbValue() will do a lookup of keyboardValue (the parameter passed) and returns a value 0..16 to indicate the keypressed. This return value is assigned to the var k.
The names are a bit misleading here. Better names could be
- int rawKeyPressed = analogread(A0);
- int key = ConvertRawToKey(rawKeyPressed);
- switch(key)
etc