Now you can move multiple columns in the Lightning report builder at the same time. Previously, this feature was available only in Salesforce Classic.
Where: This change applies to Lightning Experience in Group, Essentials, Professional, Enterprise, Performance, Unlimited, and Developer editions.
How: In the Lightning report builder, select the columns in the report table or Columns list and drag them to the new location.
Rearrange Multiple Lightning Report Columns at Once (salesforce.com)