Human resource managers face several challenges, including hiring the right employees, engaging long-tenured staff, succession planning, managing change, developing work culture during mergers and acquisitions, upholding ethics and values, balancing work and personal life, retaining employees, addressing stress and conflict, restructuring organizations, and managing a diverse global workforce. Key responsibilities involve selecting candidates that fit the company culture, maintaining employee morale, preparing for future leadership needs, adapting to shifts in policies and goals, blending different company cultures, setting ethical standards, providing flexibility, minimizing turnover, mitigating workplace issues, adapting organizational structures to changing conditions, and handling cultural differences internationally.