Horseshoes are a common symbol for luck. Historically, they have been used to "store up" good fortune, shower it down on people, and keep away negative influences.

The tradition of hanging a horseshoe for luck dates back to the 10th century. Including horseshoes in your prosperity and good luck rituals is a great way to give them extra power and focus. Even today, it is considered one of the greatest symbols of luck and protection, particularly when hung above one's door with with the points facing up

Iron-the metal that horseshoes are made from-is believed to have magical properties. Iron, like salt, has been used for many thousands of years as a potent tool in the practices of witchcraft. This makes it an ideal protective charm for everyday carry or everyday wear. Iron smells like human blood, our life force. Iron is also found deep in the earth and considered a vital force of the earth.

Thus, horseshoes could ward off witches, ghosts and demons. Horseshoes are also crescent-shaped, similarly to the holy crescent moon symbols of some ancient deities.
This is believed to repel misfortune and attract blessings.