Human resources, or HR, was a department of a workplace that dealt with personnel issues, such as hiring and interpersonal conflict.
According to an anything but canon account, a Knickersonian officer was offended by a remark that her superior officer made about an Antedian officer not getting his "knickers in a twist." In spite of his ill-perceived comment, he apologized, but she still told him that she ought to call HR. (VST: "Skin a Cat")
Ironically, the term "Human resources" would itself be discriminatory by the same standards (much like "Human rights" was to Azetbur in Star Trek VI: The Undiscovered Country), unless the meaning of the term had changed, or the significance of the "H" in "HR" had been changed by that point to mean "Humanoid".