You can delete or skip this file if you only want to play in English. The game will still work as long as you have the mandatory files (like fg-01.bin ) and at least one language pack (usually English is required for stability).
Please provide more context, including:
This article will explore exactly what this file is, why it exists, how to use it, and the broader context of game archiving that makes files like this necessary. fg-optional-portuguese-vo.bin