We have been offered to take over a rental car business, but first we have to get a LLC, How does that work?

the rental car company is a popular national chain. my wife has been istant manager for a while now. The operator of the store she worked at was fired from the big company yesterday.. The bosses have offered my wife to become owner/operator of the store. They have told her that she needs to get a LLC.? Can someone try to explain to me what we need to do now. The store has plenty of business and it would be a great oppurtunuity for us.