A famous Mahogany Town candy tourists like to buy and take home. It restores the HP of one Pokémon by 20 points.
In Black and White, RageCandyBars are available to the public. This just means they are of in demand and can restore HP by up to 20 points.
It's capable of healing all Status problems on a single Pokémon. Also, you can use them to awaken the Zen Mode Darmanitan in the Desert Resort
This is what they are used for. To heal Status problems (+HP) and/or to awaken the Frozen Darmanitan in the Desert Resort. Aka, the real purpose. It just mentions the tourists to inform you they are in the Unova region and are in use, and very poplar.
Hope this helps! •^-^•