When you get a Hong Kong entrepreneur visa, you are allowed to bring family members (a spouse and dependant children under 18 years) to Hong Kong. To bring the family members, you are required to file a dependant visa application for each of them.
Hong-Kong administration indicates that this is necessary for planning purposes. The dependants can stay in Hong Kong as long as the entrepreneur visa is valid. Besides, the dependants are also free to take gainful and legal employment and even study in Hong Kong. If you stay for 7 years and get permanent residence, the dependants will also get the same status.