If a business has 200 job openings and only 100 people apply, the business will have to make the 100 people do the work of 200 people. They might have to incorporate certain jobs into 2 or three jobs that one person could do. These 100 people will have to be paid more according to the laws of supply and demand.
If there are 200 jobs, but there are only 100 unemployed people, according to the laws of supply and demand, there are a number of possible options. Companies may have to consider making their vacancies more attractive than other vacancies. It may also be possible to recruit employees from out of state.