Final answer:
HR professionals need a blend of technical, soft, and legal knowledge to effectively manage and support a workforce in today's diverse and dynamic work environment.
Step-by-step explanation:
The critical pieces of knowledge required by HR professionals today include technical skills and industry-specific knowledge, soft skills and communication proficiency, and a strong understanding of labor laws and regulations. In a rapidly changing work environment, the ability to adapt to new systems and technologies, the capacity for critical thinking, and maintaining up-to-date knowledge of industry trends and changes are essential. These capacities ensure that HR professionals can handle various tasks, communicate effectively, and stay compliant with legal standards.