A Manual Tester plays a crucial role in ensuring software quality by executing test cases, identifying bugs, and verifying functionality against requirements. Key responsibilities include creating test plans, executing tests, documenting results, and collaborating with developers and business analysts. Essential skills include attention to detail, analytical thinking, and proficiency in testing methodologies. Typically working in Agile teams, they can advance to roles like Test Lead or Automation Tester, fostering continual growth in software quality assurance.