That data, according to the video, "describes our actions, decisions, preferences, movement, and relationships." Google uses the analogy of a ledger, with the data siphoned off the web by the internet giant being "a constantly evolving representation of who we are."
The ledger, of course, is you. And the video made it clear that Google believes you do not own the data about you, but that you are merely a "transient carrier" of it. What's more, Google suggests that over time, it could provide "more inputs" to the ledger with the goal of modifying your behavior.
One example of more inputs is Google's purchase of the marketing network DoubleClick in 2007. At the time, Google founder Sergey Brin said privacy would be our "number one priority when we contemplate new kinds of advertising products." But a decade later, Google changed its terms of service to state that your browsing habits "may be" combined with other data to which Google has access. This includes the contents of your Gmail messages, records of your Google Maps searches, your Google calendar appointments, and anything else it can scrape from your browsing records.