An umbrella insurance policy is used to cover damages to someone else's property or to cover someone's health care costs etc if you were to be sued in court for damaging someone's property or for injuring someone in a car accident.
The umbrella insurance policy will not cover damage to your own property such as property damage to your home, car, theft of items etc.
So the umbrella insurance policy does not cover anything you own that is damaged but only covers the cost of other peoples property if you're sued in court.
Having an umbrella insurance policy usually is not worth it unless you think you might be sued in court for potential damages to someone's vehicle, injuries or someone else's house.