- What you can't do
You are Functionally Fluent when you are able to easily understand any Spanish-language TV show, film, series, documentary etc. without the help of sub-titles.
In a 40-minute show you might not know the meaning of a few (less than 5) words, but you won't skip a beat because you'll understand them well enough from the context.
And you will be able to communicate (speak) anything you want to native Spanish speakers and have them understand you, though you make minor grammatical and usage 'errors'.