Most official releases support maybe 5 languages. The Multi11 tag means the repacker has stripped nothing regarding localization. You get full audio and text for:
The Mechanic: Repackers like RG Mechanics use command-line switches to compress .rpf archives (Rockstar’s proprietary file format). Instead of downloading 100GB, you download 45GB of high-density 7z archives. During installation, a decompression algorithm rebuilds the x64\audio\sfx folder for every language simultaneously, or lets you pick via a batch script.
A repack is a heavily compressed version of a game, often stripped of non-essential files (like high-resolution textures for 4K, or multiplayer components) to shrink download size. RG Mechanics is famous for creating installers as small as 30-40 GB for GTA V, compared to the official ~100 GB. However, repacks require long decompression times during installation.
Multi11 indicates the repack includes 11 language packs – typically English, French, German, Italian, Spanish, Russian, Polish, Portuguese-Brazil, Japanese, Korean, and Chinese (Simplified or Traditional). For non-English speakers, this is a major draw, as official versions sometimes lock languages behind region-specific downloads.