Freeing up space · What's Using Space (Storage Inspector)
What does the footer at the bottom of What's Using Space tell me?
Short answer: It shows how much was measured and how many places were covered, and says plainly when areas were off-limits or measuring stopped early — hence wording like "at least".
It tells you how much this pass measured and how many places it covered — and it never overstates its reach. If parts of your disk are off-limits to every app, or measuring stopped early to stay out of your way, it says so and explains what the figures do and don't include.
That's why you may see wording such as your home folder holding at least a certain amount, or that the remainder is macOS itself and areas no app may read. It also reminds you that actionable rows can be cleaned through Free Up Space.