The franchisee has to pay the franchiser for the right to use their name. This can be a fixed amount at the start and/or a percentage of the sales, but it is likely to be both. Some franchisers are so popular that there is a great deal of competition for franchises. The Body Shop, for example, receives 200 times the applicants it needs, in spite of the high cost of buying a franchise.
The franchisee has to operate the business in the way the franchiser wants. A McDonalds franchisee would not be allowed to start selling McScotch Eggs if they wanted to as it is not an approved McDonald's product.