If you did not expect this file or if the source is unknown, exercise caution. Archival formats can be used to deliver malicious content, and specific vulnerabilities in older versions of extraction software have been used by cyber actors to run unauthorized code.
You can open and extract it using free tools like 7-Zip for Windows or PeaZip for cross-platform use. Security Warning DocumentsForLilly.7z
It supports high-level encryption. If this file was sent to you, it may require a password to extract. If you did not expect this file or
A .7z file is a compressed archive created using the format, known for its high compression ratio and strong AES-256 encryption capabilities. Technical Summary of .7z Archives DocumentsForLilly.7z