Scripting refers to client-side scripting, which is mostly written in Javascript.
The Focus Inspector highlights parts of an HTML document as a user uses the tab key to navigation in the document. This is a useful feature to assess whether a document is friendly to users who can only use the tab key to navigate.
List of Events lists all the elements that can interpret events. An event is any user interaction, such as mouse clicks, hover and keyboard interaction.
It is also helpful to experiment with disabling various scripting features to assess whether an HTML document (with Javascript) remains useful when event driven scripting is no longer available.