Most guides miss this. You must manually tell the game to use English.
Alternatively, download a ready-made registry fix (search for “ACB English Registry.reg”) that sets HKEY_LOCAL_MACHINE\SOFTWARE\Ubisoft\Assassin's Creed Brotherhood\Language to 1033 (English US). assassins creed brotherhood english language pack link
Unlike modern games that download language packs on demand via the launcher, Assassin's Creed: Brotherhood (released 2010) typically ships with all localized audio and text files pre-installed on the disc or contained within the digital download. Most guides miss this
Therefore, a standalone "English Language Pack" generally does not exist as a separate official download. The English data is likely already present in your game directory. assassins creed brotherhood english language pack link
Sometimes the audio works, but subtitles remain foreign. Go to Options → Audio → Voice Language → English. If it is greyed out, your Localization.ini file is corrupted. Replace it with a clean English version from the pack.