To view data in its original state as it enters a job, double click on the data-source input node (within the job workspace) to see the titles of the columns and associated data types. Or right-click > select Preview Data to view a sample portion of the data. Previewing a sample of the data can be useful for large datasources such as databases.
However, Preview Data is prone to misleading results when using a database as a source in combination with a filter. To be certain that your preview of the mid-stream results is accurate, right-click > select View Data. You could also consider adding a temp out to your job, then running that temp out individually.