This is a tool to upload exported Flickr data (as produced by the "Your Flickr Data" option on https://www.flickr.com/account) to Google Photos, preserving the album membership.
It reads the archive metadata and stores it in a SQLite database. After importing everything, it then uploads the photos to Google using the Google Photos API. It does not modify the archives at all, and only adds the metadata to the SQLite database, so the local data that it writes is quite small.
The Google Photos API is very limited in what can be uploaded, so there is not a 1:1 conversion. In particular, there is no nesting of albums as there is in Flickr collections, so the structure of any collections is lost. Also, Google Photos has no concept of photo tags either.
This is not an officially supported Google product. This is also not an official Flickr project.