Aurora's main business is in developing military plane technology. They have several times secured contracts with NASA and DARPA. Aurora are best known for their successful funding for the second phase of the VTOL X-Plane development, defeating Boeing anndd also Lockheed Martin.
VTOL aircraft with the code name LightningStrike is promised will be able to reach a maximum speed of 400 knots and the ability to float more efficiently.
The reason Boeing buys Aurora is to help them develop the technology of VTOL aircraft and autonomous planes.
Most likely this technology will be used to make military vehicles, although it may be, vehicles made will be used for taxi drones. It remains unknown how the relationship of Aurora with Uber is now under Boeing.
With this agreement, Aurora will remain standing as an independent division under the Boeing brand. Boeing has no direct control over the company, although they provide access to financial and R & D sources to Aurora.