'ledwaarde' means the value of the led light. It's dutch which is probably confusing.
And int reading and int pitch had something to do with the light sensor. In every room the amount of light is different. Therefor i'm reading the amount of light that comes into the sensor so it can calculate whenever it's dark or not.
I don't know the exact answer because someone helped me with it.
But maybe i just have to try a different tutorial.