Focus is a critical factor in getting work done.
Your ability to get work done is a product of time and focus. Work distracted, and assignments take twice as long. Effective students have an appreciation for the importance of focus and recognize when their focus is peak and when it wanes.
Focus is a muscle that can be trained
Every time you lose focus and redirect your attention, that's the rep. It is something you can improve. The Pomodoro technique suggests doing work in 25-minute bursts with 5-minute breaks to maximize focus.
Focus is a perspective
Focus can also refer to longer timescales such as that of an entire degree or a career. Focus is essential for someone to succeed in their career because there will always be competing opportunities, each with an opportunity cost. If you understand what you're working toward, you start to see distractions for what they are.