Every chapter is written by a different author, each providing what their take on "self-acceptance" is. Self-acceptance is just that, to be able to wholly accept every aspect of who you are. In Western society, we are taught to be very judgmental, especially of ourselves and overly so. Self-acceptance is to notice those parts of ourselves that we may not like, and accept them as part of us, of who we are, and in the process learn that these inadequacies may be completely false. If they are real, so? That's just they way we are and we need to embrace the person who is "us", and not as a piece of unlovable filth.
I've seen other reviews of this book complain that it's really repetitive, which yes, it is a bit. A lot of the same ideas get said, many, many times. But each author, all of which are experts in their fields, has their own take on acceptance and compassion. I thought the multiple viewpoints were beneficial to the book. One author may not strike you as profound, but the next one could and change your perspective. Each chapter has at least one piece of information that will make you really think, sometimes for me it was just one short sentence, and that can be all it takes.
I would also recommend the book "Self-Compassion" by Dr. Kristen Neff, to be read around the same time you read this one.