The RNT guide to OV2640 camera setting is very useful but the ‘Meaning’ column is rather succinct and does not include descriptions for all the available settings.  Please does anyone know where I can find a more detailed description of what each setting does? 

The OV2640 Camera Module Software Application Notes from the manufacturer of the camera module is probably your best bet although it may have more information than you need.
I tend to just use the demo sketch and see what each setting actually does.

Hi Steve.
Thanks for you answer.
I would say the same: test the demo sketch and see what each setting does.
Regards,
Sara