Managers perform four key functions: planning, organizing, leading, and controlling. They also take on three main roles: interpersonal, informational, and decisional. To be effective, managers must have strong human, technical, and conceptual skills. The document outlines the specific responsibilities within each function and role, and the types of skills managers need, such as communicating, motivating employees, and understanding technical aspects of the job. Managers oversee resources including human, financial, physical, and information. They are classified into three levels - top managers who develop long-term strategies, middle managers who implement plans, and first-line managers who oversee employees.