What does it mean that remove what does not serve the current function?

Everything in your workspace that is not helping is hurting by creating distraction.

Example: A product designer sits down to draft wireframes for a new onboarding flow. Her desk holds the wireframing tablet, a pen, and her laptop running the design tool — and also a half-finished jigsaw puzzle, a stack of unopened mail, three books from a project she completed last month, a mug with cold tea she forgot about, and a phone face-up with notifications visible. She has not touched any of these objects during her work session. None of them serve wireframing. But each one occupies visual real estate in her peripheral field, and her brain processes all of it — the unfinished puzzle tugging at her pattern-completion instinct, the mail implying an unanswered obligation, the books reminding her of a project she should have documented. She removes everything except the tablet, pen, and laptop. The desk surface is 70% empty. Nothing changed about her skill, her tools, or her deadline. But within fifteen minutes she notices she has not looked away from the canvas once. The objects that left were not helping. They were competing.

Try this: Choose one workspace — physical or digital — that you use for your most important cognitive work. Set a timer for ten minutes and conduct a removal audit. For every object on your desk, every icon on your desktop, every pinned tab in your browser, every app on your phone home screen, ask a single question: did I use this in my last three work sessions for the function I am performing right now? If the answer is no, remove it from the active workspace. Physical items go into a box or a drawer — not the trash, just out of sight. Digital items get moved to a folder, unpinned, or closed. When the ten minutes are up, work for one full session in the reduced environment and note what you experience. Do you reach for something that is gone? That item might belong. Do you not notice an absence? That item was only costing you attention.