The job description is prioritization which is essentially saying "yes" or "no" to certain tasks. Especially in tech companies, the front line reports can always find something to do. Software developers want to automate everything or build cool things or use the latest tech. Managers are there to guide that, and that means saying "focus on A, B and C" because there's a gigantic list of tasks but saying no to 99% of that list makes the company perform better.