This video explaining setting up Lightroom for the first time and what lightroom is doing and why, has come up on the B&H site in the last few days.
https://www.youtube.com/watch?v=9ozz4EJMYec

Very well explained and essential viewing all the way through for anyone starting out with Lightroom and also demystify a few things for those also who have used it for a while.

Probably the biggest short coming of Lightroom is that at the beginning it is not intuitive how it works, what is happening and for what reason compared to how other programs do things.
By the end of the video it becomes clear to the beginner that there is method to it all and it starts to make sense as a way to handle having thousands of images.