Human resource management is a vast subject. The role of HR vertical in an organization is all about the management of manpower required against the demand and supply of a company. In a broader sense, the role envisages all the activities starting from the recruitment of weight talent, its induction training, welfare, compensation, documentation administration, discipline until exit formalities, and fulfillment of regular statutory compliance as required by the company against employees and the organization as a whole as per the prevailing laws applicable as of the date.
What's your company's business, how it operates, what all compliance it requires—all such things need to be known by HR, and must formulate a policy, guidelines, and manuals, etc. Hope this gives you some idea apart from unique terminologies like performance management procedures, KPIs, and KRAs, etc. And many more which will require excellent competency in human resource management and still it's not the end...