A high-compression archive format. You will need a tool like 7-Zip or WinRAR to open it. Common Contexts for This Naming Convention This specific naming style is frequently seen in:
Automated scripts that pull data for a specific reporting period (Christmas 2020) but are executed months later (April 2021). How to Proceed 2020-12-25 [2021-04-02_14-10-23].7z
Use 7-Zip to "Test" the archive before extraction to ensure no data corruption occurred during transfer. A high-compression archive format