HR used to be called the Personnel department in the old days.
There are normally a number of sub-functions within HR, but the one that will be interested in Moodle is the bit called "Training and Staff development", or something like that.
Typically, that bit of HR needs two things.
Certainly, they will want to track which users have completed which courses, when. There may be rules like "light-bulb changers have to go on a health-and-safety course every 12 months". They will probably also want to track people who are signed-up to do courses in advance. This, track course bookings as well as course completion. This is not really Moodle's area of strength, although there are some third-party plugins and Moodle 2.0 features that can help.
Second, they may wish to actually use Moodle to teach. This is Moodle's area of strength. That is, the may wish to move away from the face-to-face model of teaching, where staff have to leave their workplace and go to a classroom to learn, and instead adopt a blended, or completely online approach. As I say, this is Moodle's area of strength. Providing the tools that teachers and learners need to learn online.
Actaully, it occurs to me that you might do better asking your question in the Moodle for Business Use course.