Just to clear something up on this because I think (understandably) some people are getting confused with this piece of news.
Williams Advanced Engineering is part of the Williams umbrella of companies but it has nothing to do with the F1 team. It's a separate company that does what it says in the title, it's an engineering company which provides hi-tech solutions for companies using F1 style engineering and solutions.
Frank Williams is the main man obviously but Craig Wilson is the Director in charge of the company (for example)
Claire Williams for example has no connection with it. In a way it's the same operation as Williams Heritage (which is operated by her brother).
https://www.williamsf1.com/advanced-engineering/about-us
It's a separate factory, it's run by a separate group of people and so on. This is not a sale of the F1 team or part of it. It's a part sale of the Williams Advanced Engineering company.
Ironically Williams Advanced Engineering is the only profitable part of the business, which is probably why the sale took place. It's been doing very well for the last few years.
They've developed technologies for Formula E, technologies for battery powered vehicles (projects with Aston Martin for example). They've created equipment for Olympic athletes, and so on. Plus probably countless other projects we don't know about.
However, what we don't know is where this cash injection is going. I've read on numerous occasions that the WAE part of the company is deliberately kept at arms length from the F1 operation. Because it would be too easy to use profits from that side of the company to keep the F1 team afloat. Whether that position has changed I do not know, and Williams are not saying.
With the loss of a huge sponsor like Martini life was always going to be difficult for the team, in all fairness I am amazed they are hanging on. My gut feeling is they have written off 2020 already. Due to the huge difference in car regulations for 2021 they may decide to spend all their effort (and budget) on that car.