Product Page Views are the number of times users open your app's full store listing — the middle of the conversion funnel, between impressions and installs.
A product page view is counted when someone reaches your listing — whether by tapping a search result, a chart entry, an ad, or a shared link. It sits between impressions (you were merely seen) and installs (you were chosen), which makes it the pivot point of the funnel. Comparing page views to impressions tells you how compelling your icon and first screenshots are; comparing installs to page views tells you how persuasive the full listing is.
Tracking page views by source is where it gets useful. A search-driven page view is a decided, high-intent visitor; a browse- or ad-driven one is more curious than committed, and the two convert at very different rates. Knowing where your page views come from — and where they leak — tells you whether to invest in ranking, in conversion, or in a more targeted traffic mix.
Example
An app sees strong impressions but its impression-to-page-view rate is poor, pinpointing the icon as the leak; after a redesign, page views climb and installs rise with them — no ranking change required.