Definition of 

App Store search

What's 
App Store search
: it is one of the possible values for
Source Type
. It means:
Users who discovered your app within search results on the App Store. Includes Search Ads results. Doesn’t include the Suggested section of the search landing page.

See other fields from

Analytics: Installations and Deletions

Explore more Reports from

App Store Connect

The (only) data hub made for apps