Rudraksha is the seed of a particular tree species which usually grows at a certain altitude in the mountains – mainly in the Himalayan region. It plays a very important role in a spiritual persons life and is used as a kind of shield against negative energies.
You may think nobody will do negative things to you, but it is not necessary that it should be targeted at you. At times, it is not intended for you, but it can happen if you are in the wrong place at the wrong moment and your aura is weak or unprotected.
There need not be a huge fear about such things, but a mala is believed to be a protection from that negative force. Sometimes worn on the body as jewellery and other time hung in your car to protect you on your journey.