Will somebody tell me what this means and what I'm supposed to do with this information?

[phoebe_figalilly]

Project Recovered
The project was not saved properly the last time Audacity ran.
It has been recovered to the last snapshot, but you must save it to preserve its contents.

[waxcylinder]

It means:
a) Audacity crashed
b) when you relaunched Audacity offered automatic crash recovery of your project.
c) the message is advising you to Save the project (or use Save Project) to preserve its current state before doing further editing.

Peter.