The Topic Structure Wizard identifies how new topics will be created, according to the rules in a profile. It shows each paragraph style that is found, the outline level that will be used in the book contents, and the template on which the new topics will be based.
This is where you can adjust the outline level and topic template that will be used. For example, you may have defined a style in the document that has not been picked up by the current topic creation rules in the profile, and you want to use this style to signify a break for a new topic. You can select this style and change the level, and apply a topic template. Author creates a temporary rule, which you can save at the end of the import.