So, what is it actually selling? Much of it is information. Personal information about us, the users of its services. We are the product.
Big Brother has been with us for a long time, but not exactly in the form George Orwell imagined it in Nineteen Eighty-Four. For one thing, surveillance is owned and run by private enterprise. For another, it is much more thorough. Thirdly, it is almost invisible.
And here is how Google harvests the product it sells: https://contrachrome.com/
Considering the growth in revenue

and profit

there'll be more of that in the years to come. Much, much more.