Reducing the water pressure reduction?
Probably you can. The picture is indeed very blurry. You'll need a biggish screwdriver, and a wrench. You hold the screw steady with the screwdriver while loosening the nut, then turn the screwdriver a bit (don't go crazy) and then hold it and retighten the nut. Having a gauge installed and checking the pressure when nothing is drawing water, but also when things are will give some insight as to how well it's working (sometimes "low perceived pressure" and "PRV not working as it should" are related.)