Report label - is a report element headline text.

Manage documents labels text and translations at: Tools → Company Settings → Report Labels.

The document can be exported to Crystal Reports format (.rpt) to see how elements located in the same markup - requires additional software installation.
Or exported to .xml format: the tags <Field Name> keep the labels in front of its value the same as they are called in Application - no additional software is required.

Brands
Report Settings

Here are Invoice documents assigned to different Brands, with their own templates codes and labels: