This is a list of some product, like
books or
video games, that shows what
book or
video game is selling the most
copies.
For instance the
NY Times runs a Best Sellers list.
So does
Amazon.com.
Diffrent retail outlets like to get togeather on the top selling
vgc and
computer games for a list. (Which unfortunately put's several million one dollar copies of
Deer Hunter at #1, most of the time, hence proving it's
marketing, not quality, that makes a best seller.)
There are also often Best Seller Lists of movies, which aren't called Best Seller Lists, because they are selling
viewings via
tickets, which explains why it's called "The top movies at the
box office."