The answer is, whatever you want it to be!
The Meander Accordian Folded Book has many aliases, so is it any surprise it can be whatever book you want it to be? (This link has a video tutorial if you are that way inclined.)
I made this one to gift to a friend's 5 year old girl - the idea is that she can fill each of the 16 pages with her favourite things. I gave suggestions of favourites, such as favourite song, favourite animal, favourite saying/quote, favourite thing to do, etc...you get the gist. I am thinking I have to do one of these for each of my children each year. This can be my answer to scrapbooking which I know I am not discipline enough to do. The children each can fill their new book each year on their birthday - wow, imagine a collection of these little books for each child journalling how their favourites have change over time. Hmm, I like....
Next one of these I make will be a Baby one - for a newbie born at the beginning of this week.