By the way, NP stands for "Nicht Potentialfrei"
Potential-free means that you can work with two different voltages on the input side and the output side.
With non-potential-free, input voltage = output voltage (in this case 230V).
Potential-free outputs are often used for inputs of a PLC, DDC, etc., i.e. an application with a controller or control device behind it.
In your case, where you only want to switch a lamp on/off, it therefore does not matter...