List | Notion

Item, which corresponds to the node that displays an item in the list (it is repeated automatically for each item)
Empty, which is the node to display when the list contains no items

The List node declares two variables in each item:

item which contains the data corresponding to the item (it can be a variable of type text but also a more complex object)
index, a variable of type number which corresponds to the position of the item in the list (the first being 0 and so on)

By default, List is created with a list of text, and each item contains a Text connected to the item variable, thus a text. However, it is possible to create lists containing more complex objects.

Finally it's important to know that the node doesn't take care of the container appeareance. In other words, you can either create a list within a Section, a Grid, or any other container node.