This is a simple version of a webshop. It allows you to add the shopping possibility to a common content type. Not so big as Commerce but sometimes it is sufficient. The buyer and admin gets an email after buying. No online payments but TVA,... is present.
The commerce module has to be installed with Composer..The Commerceguys provide now an alternative. With Ludwig one can install Commerce without composer. The Ludwig module (Ludwig von Beethoven was a deaf composer --Drupal fun--) shows the manual way.