To be conversational in any language is being able to carry on a basic conversation, like the way people talk to friends and family. Like: ¨Hello, how are you? I am fine, thank you.¨ etc.

To be fluent is to be able to talk about any subject intelligently. Example: ¨The economy is in a slump. Please give me your opinion on how we can make it improve.¨

I think they want to say: I can talk in Spanish,but not very fluent. 

Thank you, Toni. I can't recall having used this term when I was deep in language teaching methodology a long time ago. I'll have to try and find it in more recent papers. 

first time I hear this word

we need one explain it