What does it mean that drill down and zoom out as thinking operations?

Moving between levels of hierarchy is an active thinking technique.

Example: A product manager notices declining retention metrics. Zooming out, she sees the problem is concentrated in one user segment. Drilling down into that segment's onboarding flow, she finds a single confusing step that causes 40% of drop-offs. Zooming back out, she realizes three other products in the company have the same onboarding pattern. The fix is not a single UI change — it is a design principle applied across the portfolio. She could not have reached this conclusion staying at any single level.

Try this: Pick a problem you are currently working on. Write it down at three levels of abstraction: (1) the broadest framing — what is the category of problem this belongs to? (2) your current working framing — the level where you have been spending most of your time, (3) the most granular version — what is the specific, concrete instance right now? Read all three. Which level have you been stuck at? Move one level up or down and spend ten minutes thinking from that new vantage point. Notice what becomes visible.