Taste means whether sweet, sour, salty, bitter, pungent, bland or a combination. Different tastes have different actions. In brief, sweet tonifies, sour astringes, salty softens hardness, bitter clears heat, pungent disperses and bland acts as diuretic. Substances are classified according to their most prominent effect on the body, which differs somewhat according to the classifier. Actions mean such things as dispersing the surface, clearing heat, draining dampness and so on.
Indications mean specific patterns of illness treated with the medicinal.
Viral infections are seen as a form of heat or fire in Chinese medicine, so antivirals are known to be cold by nature, as are antibiotics. Vitamin C, goldenseal and echinacea are also cold by nature. This is why vitamin C irritates the stomach at high doses. Coldness leads to strong fixed-location pain. Coldness in the stomach produces knotting pain.