It’s a mod or configuration data for a specific engine. .csv , .sql , .xlsx : It’s a data export or database dump.
Once you look inside, the file types will tell you what it is: It’s a graphics/texture pack. LoOnly_Po-008.7z
Because .7z files can contain executable scripts or malware, use a "sandboxed" approach: Use 7-Zip or WinRAR. It’s a mod or configuration data for a specific engine