Commercial umbrella insurance is a form of excess insurance that gives you extra financial protection when lawsuits exceed your primary business insurance limits. For instance, a customer slips at your store and sues for $2 million, but your general liability only covers $1 million. Your commercial umbrella coverage would handle the remaining $1 million.
You can't buy commercial umbrella insurance as a stand-alone policy. You must first have existing business insurance, then add umbrella coverage.