Umbrella insurance covers physical and moral damages that you may have involuntarily caused to a third party. The most common claim made under Umbrella insurance is a lawsuit.
For example
You go to Vermont for a family weekend getaway. You are driving along serenely when, all of a sudden, a deer leaps across the road causing you to lose control of your vehicle, which veers into the opposite side of the road and hits a car containing two passengers. One of them dies and the other will suffer lifelong physical injury. An investigation reveals that you are at fault for having caused the accident. What do you need to pay? Ambulance, police, firefighters, medical costs, funeral costs, income loss, loss of use of the person who ends up with a disability, loss of use of the family of the deceased… Thankfully, you have Umbrella insurance and you have avoided yourself a huge headache.