What do HR managers and departments do today?
I have edited your question a bit, but I am not clear on what "their contents" means. There are many functions in today's HR department, so let's talk about that. I do want to caution you, though, that different organizations may vary somewhat in how they use their HR resources.
Often, HR departments are responsible for hiring, discipline, and termination. In some companies, this department makes these determinations on its own, while in other companies, a manager or someone higher in the company will make final determinations, and the HR department will simply screen and/or gather information to assist the decision-maker.
Often, HR departments are responsible for training employees initially or for providing continuing education for employees. Some companies do outsource this, though.
Another function of the HR department is often the administration of unemployment compensation. This might include everything from vetting a termination decision to see if it will result in a UC claim to representing the company at an unemployment compensation hearing.
Still another function of the HR department is the administration of state and federal statutes, for example, the Civil Rights Act, OSHA, and the FLSA.
HR departments are often responsible for the administration of benefits, including sick and vacation leave, and employer-provided life, health, or disability insurance.
That is not a comprehensive list, but I hope enough to get you thinking.
In the modern workplace, HR stands for Human Resources. According to the Wright State University, HR can be defined as the department with deals with "people issues" in an organization, focusing specifically on "employee behaviors."
As an HR manager, an individual is expected to oversee all aspects of an employee's working life. This starts at the very beginning of a person's career with the recruitment process and continues to include vacations, health and well-being, pensions, pay, and workplace safety. It is their job to implement the organization's policies and procedures in all of these key areas.
An HR manager is also expected to maintain a happy and efficient workplace by ensuring good relationships between the various staff members. If any issues or disputes arise, then it is the HR manager's job to respond in a timely and proactive manner. Failure to do so can make it difficult for an organization to function well and to retain its staff, so the HR manager plays an important role in the modern workplace.