There are several possibilities for what you might be thinking of:
* A typo: Perhaps you meant a different language with a similar name. Can you double-check the spelling or provide more context?
* A fictional language: Some fictional works, such as books or movies, might use a made-up language called "Bo." If you remember the source, we might be able to identify it.
* A regional dialect or slang: Some languages have regional dialects or slang that might sound like "Bo." Do you remember where you heard this term?
Please provide more information so I can help you understand the language you are asking about.