The Data Dictionary can generate a report for all of your objects and fields, plus some org information, like org licenses and org limits. When you first come to the Data Dictionary report, you will see three columns. The left column will show all of your custom and standard objects. You can highlight one at a time to show in the preview report tab, or you can check the green box next to multiple objects to pull them into the display report tab.
The middle column includes all of the elements of the report you have selected in the dropdown at the top of this column. You can choose elements of your objects, fields, or org reports.
Once you've selected the objects/fields and their elements you want report on, you can navigate to the Display report tab. On this tab, you can color code your tabs to highlight certain results.