You are only able to view columns and fields on reports that your administrator has given you permission to view. If you are granted permission to view a report that contains individual fields that you do not have permission to view, the restricted fields are dropped from the report.
The behavior is such that not only will you not see fields that you do not have permission to view, but these same fields will be dropped from the report preparation, if they have been used as report filters or summary columns on a Summary report. If you have permission to view a report, but you do not have permission to view any of the fields on the report, ExtraView will offer you a message that tells you that you do not have permission to view the report.