From what I can tell it's:

* extra storage (google drive + google photos + gmail).

* phone photos and contacts backed up (there's a Google One app)

* "access to experts"

* discount on google purchases in "Google Store" - so for Pixels and DayDreams? Does Stadia count?

* discount when booking hotels through google.

Super weird mix of features. The meat of the offering seems to be more storage.