The five coins represent the 5 emperors that has ruled in China, Shuen Zi, Qian Long, Yong Zheng, Kang Xi, Jia Qi. When these 5 emperors ruled, the country was well and was not corrupted.
These coin can prevent "bing qi" / illnesses. Without magic spells, buying such coins will have no use, Master Tu has enchanted these coins with magic spells.
This is a great present for friends and family.