An HR Generalist more of an all rounder. In HR there are specialists or you can also call them SME (Subject Matter Experts) of HR domains like Recruitment, Employee Relations, Training, Payroll etc..
So to your answer: HR Generalist is a person who single handedly administers to all the domains within an organization which is no child's play - trust me on that!
Human resource generalist – an individual with knowledge of all aspects of human resource management. The generalist helps managers address a wide variety of human resource issues and resolve specific employee problems.
Human resource generalists have demonstrated value to their client managers by taking responsibility for many operational human resource activities, including defining jobs, recruiting and selecting new hires, addressing performance issues, handling terminations, arranging for or providing training, determining and implementing salary changes, explaining and administering benefits, and addressing employee relations problems as they arise. The generalist role, at its best, is perceived to be a “one stop shop”, providing the full range of services managers require to manage their people. Managers expect their human resource person or team to “do it all” and to be responsive to the business’ changing needs.
With changes in the human resource function, however, the generalist role may well be obsolete. As operational human resource work is redefined, automated, or taken over by external vendors and internal shared services, the role of the human resource leader is changing. Leaders are finding it difficult to sustain the full-service role that their manager and employee customers have grown accustomed to. Now they face the challenge of shifting their roles (and their value added) towards consulting and leadership on human resource strategy and change management.
Hope this post does not put you to sleep but sheds some light on what a HR GENERALIST is and how the roles of an HR professional are changing with new challenging businesses.