Freeing up space · Temporary files and Storage Studio's own footprint
What does the banner naming one app at the top of the temporary files list mean?
Short answer: One app accounts for a large share of your temporary and cache areas. The rows clear the symptom; the banner points at the cause, so check that app's updates or settings if it keeps happening.
It means one app accounts for a large share of what's in your Mac's temporary and cache areas. The rows below deal with the symptom — clearing what's there — while the banner points at the cause.
If the same app keeps appearing, it's worth checking that app: updating it, changing its settings, or contacting its developer can stop it leaving folders behind. Storage Studio's space watch will also tell you if it starts growing fast again. See how the space watch works.