Holdings reports are available on the Content page of the Librarian Portal.
The reports include all content your institution currently has access to on SpringerLink, nature.com, ScientificAmerican.com, SpringerMaterials, AdisInsight, and Nano.
You can use the reports to understand which content you currently have access to. The files can also be used to update holdings in many discovery systems. Discovery system updates can also be automated, see KBART Automation.
The reports are KBART Automation files, as described in NISO RP-26-2019, section 2. In short, each row represents an active license for one title. If you have access to several ranges of issues for a journal, each range will have its own row.