When it comes to how something works, modern scientific biomedicine is very keen to understand medicinal mechanisms. While it is true that traditional Chinese medicine doesn't make use of microscopes or molecular models to explain the effect of our therapies, we do have a very well developed theoretical framework to explain the actions of herbs.
TCM (traditional Chinese medicine) gives herbs certain qualities such as its temperature, taste, and the channel and/or organ that the herb enters.
Herbs have a sort of thermal quality about them. For instance mint is cool and peppers are hot.
Herbs also have tastes such as spicy (also called pungent or acrid) sweet, bitter, salty, sour, and bland. Each of these tastes have medicinal functions associated with them. For instance, sweet and sour together are one way to stimulate the production of body fluids. If you think about how sweet and sour tastes in your mouth you might get an intuitive sense of how the body responds to these tastes used together. As they make your mouth water, so do they hydrate your body.
Finally, herbs have target organs and channels (these are the acupuncture meridians associated with the organs). An herb that is described as entering the Liver or the Kidneys has an effect on those organs as well as the channels associated with those organs. Effecting the channel often means that the part of the body that will benefit from the medicinal properties of the herb will lie on the trajectory of that channel. For instance, an herb for Stomach Fire might address heartburn in the Stomach, but also bleeding gums which is an area through which the Stomach channel passes.
One final thing: when I describe an organ with a capital letter such as "Liver" or "Kidney". This is the TCM concept of this organ which differs somewhat from the biomedical assumptions. For instance, the heart pumps the blood, but the Heart stores the spirit and thus is implicated in some anxiety states and insomnia.
So when I describe an organ with a capitalized letter, don't go running to your doctor complaining of a Liver problem because it may not have anything to do with your liver. : )