Freeing up space · Storage Profile, charts and Home
What does "What you actually work on" show in the Storage Profile?
Short answer: It shows the files you've opened recently — your real working set — against everything you store, by type and folder, with an expandable list you can reveal in Finder.
It shows your real working set — the small number of files you've opened recently — compared with everything you store, for example how many files you've worked on in the last 30 days out of all those stored.
It breaks them down by type, shows the folders you work in most, and has an expandable list of the files themselves grouped by category, with each file's name, location, when it was last opened and a reveal-in-Finder button.
It's a useful way to see how much of your disk is genuinely in use — the rest is often a candidate for your fast drive. See Where it lives.