its just connecting two contact points we sometimes do this when fuses burn out, usually on screens and the wifi, if the fuse on the screen goes you bridge it and the screen will work again the screen can only then short out and you will need a new one but if you hadn't bridged it you would need a new one anyway
basically it is only used when something is wanted to be purposely broken/fried or when it will fix something that cant be fixed any other way and will only produce a positive outcome, like the screen working again