Within the Report Builder there is a tab called 'Grouping'
Grouping allows you to pull together multiple leads into a single row on the report based on the field name you are using and the value in that field.
For example, if you are trying to pull a lead report for how many valid leads two different Publishers Delivered, the grouping tab allows you to have two individual rows, one for each Publisher and each one with their total amount of valid leads.