It doesn’t. Reflexology is made up pseudoscience that can not and will not work. It is junk.
The theory behind reflexology is that different organ systems in the body are reflected to the feet, so that can be used to help diagnose systemic illnesses in these organ systems. The theory further says that stimulation of these locations on the the feet can help treat illnesses of those organ systems. There is not one shred of evidence that links any organ system to the bottom of the foot in the way that is claimed by those that promote reflexology. It is simply made up nonsense and physiologically impossible.
There is not one well done, blinded, controlled study that shows that reflexology works. There are some poorly done studies without control groups or other flaws that do try to claim to show that it works. The poorly done studies show it works, the well done studies show that it does not. The systematic reviews and meta-analyses on reflexology of all the data have all concluded the same thing that reflexology does not work.
HOWEVER, a lot of studies do confuse reflexology with a damn good foot massage. Giving someone with a chronic health problem or condition a really good foot massage will probably make them feel better as they are relaxed and chill out during the massage. That is not reflexology that claims to stimulate specific areas on the foot to help the disease.
There is nothing like getting a damn good foot massage to feel better and relaxed, just do not call it reflexology or try to use the pseudoscience junk science to explain why it makes you feel better.