Taking your question at face value, it's a "Book Report" on the book entitled "Practical Doomsday".

So there's a book called "Practical Doomsday" which Larry Hosken has read, and this is a brief report on what the thinks people might be interested in knowing about the book before they make a decision whether or not to acquire it.

I'm guessing from the tone of your question that you don't care about the subject, but others might.