Definition of 

Redownload

What's 
Redownload
: it is one of the possible values for
Download Type
. It means:
A subsequent installation of an app onto a device by an Apple ID account. Counted when a user taps the redownload button on the App Store.

See other fields from

Analytics: Installations and Deletions

Explore more Reports from

App Store Connect

The (only) data hub made for apps