First of all, HR should assess the working capacity of the company. How much strength is actually required in the enterprise? Once it is correctly estimated, then they can work on how to procure them. After this step, they need to keep on assessing how the respective employees can be managed in the most efficient manner. So you see, it is more like planning how to drive a car. The only difference is that there are many drivers, each having a distinct role in running the automobile!
But can the work of the HR be that simple? No, they have to constantly assess whether the employees are able to deliver the desired output. The more voluminous an organization is, the more complex is the process of running it. The HR department needs to maintain the sync and needs to connect the required employees. The targets ought to be achieved in an easy and effective manner.
If there is a lapse of any kind, then they need to assess how to solve that particular problem. Can it be solved at a grassroots level? Or does it require the intervention of the higher-level authorities? Either way, the HR department has to ensure that in no way there should be any disruption in the hierarchy of employees. They should be quick and agile in finding out if there is any problem or not.