In a Websites for Trello website, just like cards are pages, lists are categories.
Lists constitute the basic way of organizing content. All cards inside a list will be assumed as belonging to the category defined by that list.
The list's name will be used to name the category and to create the URL of the cards inside it. For example, a card named "Hello world" inside a list named "This category" will have the URL
All lists/categories are also, by default, shown in your main navigation menu that appears in all your website pages.
If the first character of a list's name is a
_, it is not shown as a category and all cards inside it are not published. This is an easy way of having a private list just for notes, ideas or drafts.