Once you've established your ad platform and Google Analytics data sources, Funnel will start importing your data. Although you'll most likely want to teach Funnel how to categorize the data from your various data sources (by traffic source, market, or campaign, for example) you can start exploring the raw data straight away.
When looking at the Data Source dimension in the Data Explorer you'll see one row for each of your data sources.
Since each row represents a data source, some metrics only have values for some rows. Cost, for instance, is pulled from your ad accounts and not from Google Analytics, which is why rows showing Google Analytics data sources do not show any cost.
The same logic explains why Sessions, which is a metric pulled from Google Analytics, can't be shown on rows for ad platform data sources.
Understanding your raw data
Analyzing your data per, for example, traffic source, market, or campaign with the data from the various data sources mapped together requires teaching Funnel how to think of your data. This is done by creating dimensions, which we cover in another article.
However, before creating dimensions it is useful to look into the raw data to understand what data you have available and how it looks.
Hitting the "Fields" button above the table opens up the fields selector which lets you choose what you want as rows in the table. Under the headline "Data Source" you'll find the segmentations your raw data comes with.
If you, for instance, select Data Source type name type and Ad campaign name as your two dimensions the table will show two columns with dimension values, listing all campaign names found in your ad accounts along with each campaign's data source type:
Similarly, you can inspect your Google Analytics data by selecting to show GA Source, GA Medium and GA Campaign as dimensions in the table:
The data you're looking at now is in its raw form which can be tricky to use for understanding how cost relates to transactions, for example. As mentioned above, doing that analysis requires teaching Funnel how the data from the various data sources are related.
However, having an understanding of how the raw data looks and how to access it is helpful in understanding what possibilities you have when grouping the data by creating dimensions.