: Download the official, open-source tool from 7-zip.org . Avoid any other domain to stay safe.
“7-Zip install and tutorial: The best free file archiver you'll ever need” YouTube · Mr. Sujano · 5 years ago
The file is a compressed archive created using the 7-Zip software. Based on its naming convention, it likely represents a specific data set or build (possibly "HL" version 01, iteration 20), though the exact contents depend on the source you downloaded it from. Technical Review
: Right-click HL_01_20.7z , hover over "7-Zip," and select "Extract to 'HL_01_20'" to see the internal files without cluttering your desktop.
: The .7z extension uses the LZMA/LZMA2 algorithm, which generally provides better compression ratios than standard ZIP files.