Fluency in English (or any language) is a very advanced level of knowledge of the language. To be fluent in English means to speak easily and freely. I don’t think there are different “kinds” of fluency. You cannot be a little fluent in a language. It’s either you’re fluent or you’re not. Your English might be good, even great, but you are fluent in it when your English is superb. I’m definitely not there yet, but I hope to be some day.