Facebook supported 111 languages as of January 2021.
That figure refers to languages officially supported by Facebook’s interface and related platform functions at that time. It did not mean that Facebook users posted in only 111 languages; people could publish content in many more languages, even when menus, help resources, translation, or moderation tools were unavailable or incomplete.
Facebook’s language coverage grew from a much smaller starting point as the service expanded internationally. Arabic support, introduced in 2009, was an important example of the platform adapting to a major non-Latin writing system and a large regional audience.
The number can vary by date and by definition. A language list may count interface locales, translation languages, or languages detected in user content differently. That is why the January 2021 date matters. For this time-specific wording, 111 is the canonical answer rather than a current-language count.