@gnu2 What do you mean?

> what do you call someone who only speaks one language?

The answer is not American. In the world, Some people don't use English.

I am not English native. I can understand Japanese perfectly. But I cannot understand English perfectly.
Please use plain English, or you may use Japanese. I do not use difficult Japanese phrase to foreigner for communication. I want you to be considerate for foreigner (non English native, because you are English native).