A synopsis, from my approach to it in the past, is that it quickly summarize the main characters and plot of the novel, so a bullet list is pretty close to how it will read. Just try to finesse it into sentences and paragraphs. I am sure there are others with more experience than me on this, but my guess is your critiquer wants to know what the book is about and what to expect from it with more than just a book/blurb. Good luck!