Human Resources refers to staff management in a company.
Wikipedia explains it as:
"Human resources is a term used to describe the individuals who comprise the workforce of an organization, although it is also applied in labor economics to, for example, business sectors or even whole nations. Human resources is also the name of the function within an organization charged with the overall responsibility for implementing strategies and policies relating to the management of individuals (i.e. the human resources). This function title is often abbreviated to the initials 'HR'."
That's a pretty solid description of it too.