Allen has segregated his asset ownership so each new operating business he owns is owned through a separate limited liability company or corporation and that all of his passive investments are held by a family limited liability company. He owns the interests in all of his entities through a family holding entity.
This segregation has taken place so that if one of his operating companies is sued his risk is limited to the market value of the assets of that entity. That is what it means for the liability to be limited.
The holding entity is also an important part of this structure. The role of the holding entity is to do nothing but hold interests in entities. It owns no assets other than interests in other businesses.