At first glance it's quite clear. When a Cylon dies, his (digital) consciousness is uploaded to the resurrection hub and there it is downloaded to a new body.
But on a closer look there are many open questions:
- It seems that the range of the upload is far greater than the usual communication range of the Cylon technology.
- If a Cylon is destroyed completely (or his head or wherever his consciousness is stored) how could it be uploaded after that? (e.g. destroyed raiders)
- Why don't they have more resurrection hubs?
- How could a biological Cylon be able to upload his consciousness despite of being indistinguishable from humans by medical examinations? The mechanisms for that (and by the way for interfacing with a wire in the arm) should be detectable by colonial medical technology.
And I could find probably more questions. So is there any official explanation how the resurrection works?