A click shows that a reader was interested enough in your book to visit its retailer page. It does not necessarily mean that the reader completed a download or purchase.
After clicking, a reader may decide the book is not the right fit after reading the description, looking at reviews, checking the price, or viewing other information on the retailer page.
Readers may also click with the intention of returning later.
The Fussy Librarian can measure clicks to retailer pages, but ebook retailers generally do not provide us with data showing which individual clicks resulted in downloads or purchases.