The number of reads shown in below the book cover or next to it is just the total number of reads on all chapters of the book. Not the number of people who read the book. If it was the other way around it might have been more accurate. It's not like YouTube.

Even if you watch the same video on YouTube a billion times and no one else ever watched it, the view number will remain the same "1"

Unlike Wattpad where someone will read the chapter a few times and all of them will count.