PowerBI Data Sources

Hi all, 

Relatively new user to PowerBI (And my current business) here. 

An ex-employee has created a few dashboards which are currently published for the wider business to self-serve. A new source data table however has since been created for consistency reasons and it is currently my responsibility to ensure that all current reports are calling from this dataset. 

From my knowledge, I know the colleague managed to get around to rebuilding a handful of reports, but there is no documentation to suggest which was still require rebuilding. Therefore, I am currently going through all the reports, in the desktop version, and understanding where the source data calls from.

I usually head into power query editor and click 'edit settings' on the soure and usually a SQL statement pops up to show me how the data was extracted. However, on a few reports there is no query in the select statement, but only a reference to the server which is being used. 

On the 'Applied steps' part of the dataset, there is source and then 'Navigation'.  Would someone be able to explain how the data is being extracted without the use of a SQL statement?

Does this have something to do with Import vs Direct Query? 

Apologies in advance, still getting used to using this software. 

Thanks,

CC