Products are the broadest category in Bugzilla, and tend to represent real-world shipping products. E.g. if your company makes computer games, you should have one product per game, perhaps a "Common" product for units of technology used in multiple games, and maybe a few special products (Website, Administration...)
Many of Bugzilla's settings are configurable on a per-product basis. The number of "votes" available to users is set per-product, as is the number of votes required to move a bug automatically from the UNCONFIRMED status to the NEW status.
To create a new product:
Select "products" from the footer
Select the "Add" link in the bottom right
Enter the name of the product and a description. The Description field may contain HTML.
Don't worry about the "Closed for bug entry", "Maximum Votes per person", "Maximum votes a person can put on a single bug", "Number of votes a bug in this Product needs to automatically get out of the UNCOMFIRMED state", and "Version" options yet. We'll cover those in a few moments.