Zen Cart allows you to display information about who manufacturers a particular product.
This information can be displayed on your product page, either as text (the manufacturers name) or the manufacturers logo, depending on how the site is setup.
Example of Maufacturers sidebox, this provides a list of all the current Manufacturers and lets site visitors view all products by that Manufacturer by simply clicking on a name
It also allows site visitors to find products by a particular manufacturers (depending on site set up, links can be created to show products from each manufacturer).
To add this information to you products you must first add a list of manufacturers to your site, then when you add products you can assign each product to a manufacturer.