Short explanation: Beta Readers are folks (often fellow writers, but not exclusively) who read your manuscript and give you feedback. The feedback can take on just about any shape - from formatting to dialogue to plot to structure to punctuation, and everything in between.
A little while ago, I (nervously) sent the manuscript of Frisky Business to six people. They all got back to me fairly quickly (which in itself was a very good sign.)
Wow! What a cool process this beta reading thing is! The overall reactions were positive, very positive, and obviously that made me do a happy dance! Yay!
But, despite the loads of good karma these six people gave me, they also offered criticism - constructive, well-intended criticism.
I'm so very glad they did!!!
As I read through their comments, I found myself nodding in agreement. I thought to myself: "Yes... Good point! ...My gawd, he's right! ...Wow, her suggestion is terrific!" and so on.
It's a good feeling to try something new and to have it work out so well, so satisfyingly. That's probably because I was smart enough to choose good Beta Readers.