Can the Arduino handle lots of variables?

One more thing!
If I do this:

if(buttonVal[0,1,2,3,4,5,6,7,8,9,10,11] == bounceCheck[0,1,2,3,4,5,6,7,8,9,10,11]){           //if val is the same then not a bounce
    if (buttonVal[0,1,2,3,4,5,6,7,8,9,10,11] == HIGH && buttonState[0,1,2,3,4,5,6,7,8,9,10,11] == 1) {   //check if the input is HIGH
     // digitalWrite(ledPinOne, LOW);         //turn LED OFF
      midiOUT(0x90, 60, 0); //Note ON (CH 1), middle C, zero velocity turns note off
      buttonState[0,1,2,3,4,5,6,7,8,9,10,11] = 0;
    }
    if(buttonVal[0,1,2,3,4,5,6,7,8,9,10,11] == LOW && buttonState[0,1,2,3,4,5,6,7,8,9,10,11] == 0){
     // digitalWrite(ledPinOne, HIGH);       //turn LED ON
      midiOUT(0x90, 60, 127); //Note ON (CH 1), middle C, velocity 127
      buttonState[0,1,2,3,4,5,6,7,8,9,10,11] = 1;
    }

  }

Will it check each button in the array individually, or will they all have to be pressed or something weird?