You often hear that so-and-so is "fluent" in one or more foreign languages, as if this were the hallmark of language acquisition. Well... it isn't, necessarily. Fluency involves fairly rapid and unbroken delivery of speech. This doesn't always imply that the language delivered is grammatical, with a well-developed vocabulary, or even comprehensible in terms of pronunciation.
Accuracy and fluency tend to have an inverse relation in language delivery (when one goes up, the other goes down). It is not hard to see why: if you are not self-monitoring and hesitating to find the right word or correct syntax, you can speak much more quickly. The ideal of course is to have both accuracy and fluency, but this is achieved (when it is achieved) at a late stage.
In my experience, there are various factors that determine whether accuracy or fluency will prevail at a given time with a given speaker. One of these is personality (those who are shy will be more accurate), another is gender (men often are fluent to the detriment of accuracy), and also life experience (those who must speak for practical purposes are more fluent and less accurate, those whose knowledge was acquired academically are more accurate).
Language learners should strive for both, although accuracy should prevail in the early stages- if one gets used to mistakes in grammar, vocabulary and pronunciation, they will be harder to eliminate later. Once a solid basis has been attained (intermediate, upper-intermediate level), one should focus on fluency.