How do you answer this question? Many people think that if you don't hesitate and your accent isn't obviously foreign, then you speak the language well. This is only one facet of overall proficiency, the one on the surface that gets everyone's attention as a marker of being able to use the language. But this can be quite subjective. You may say something meaningful but the native speaker listening to you may focus only on your pronunciation flaws. Likewise, you may say hardly anything at all. Maybe your "Hi , how are you?" has a near perfect accent, native-like flow and you could be told you speak wonderfully. However, for us language educators we think about proficiency as a continuum and look not just at aspects like these but more at what a speaker can do with the language in broader terms.
There are a couple of scales that describe different levels of proficiency that are used in the United States. The government has their own- the ILR (Interagency Language Roundtable) scale which is basically used to test their own personnel, for example people who wil be going to fill a post overseas and need to use the language of the host country at a high level or in a professional capacity. This scale goes from 0 (no functional ability) to 5 (highly educated and articulate native speaker). See the speaking descriptions here.
This scale is appropriate for its applications used by the government, however since it includes much higher levels of language than are typically achieved by students in formal settings, in academia, the ACTFL (American Council on the Teaching of Foreign Languages) guidelines are more commonly used.
The ACTFL guidelines' major levels go from Novice to Superior and these correspond with the ILR scale's 0-3. See the descriptions here. There is something very important to keep in mind when reading these descriptions and that is text type. For example, novice speakers can only used memorized phrases intermediate speakers speak at sentence level and advanced speakers can communicate in cohesive paragraphs. Superior level speakers can handle extended discourse. Advanced-Low is the minimum level required for teacher certification in commonly taught languages in some states. These guidelines are applied through an Oral Proficiency Interview (OPI) with a certified tester. The OPI measures global proficiency and takes the form of a conversation but there are no pre-set questions. Topics are determined by the interviewee's background, experiences and level as the interview progresses.
I first read the guidelines when they were new in the 80's, in a textbook for learning to teach Spanish. They since have been revised, but at the time, I got the idea from reading them that if you knew all the grammar and could use it spontaneously in conversation then, you were at Superior. But that didn't take into account text type, so you could be able to say sentences like "si no hubiera llovido, habria ido al parque" but if they are not part of a complete, connected story or part of a longer, more complex discussion on abstract topics, then you would only be rated at an Intermediate level. Likewise, I thought that since Superior was the ultimate level, implying that those speakers made hardly any errors, native speakers would fall into this category. However, when I went through the OPI tester training, I got a more accurate picture of what the guidelines were about. What was most surprising, as our professor explained, was that in our own language we tend to speak in the Intermediate and Advanced range in our day-to-day conversation. Granted, the native speaker will have better pronunciation, flow and accuracy than a learner but the text type is sentence and paragraph level. It's the back and forth, question and answer and anecdote telling of casual speech. The higher levels are not as common in the average conversation but are rather either more formal or more linguistically complex such as the language of debates or that needed by diplomats.
So, if your accent isn't as good as you would like it to be, remember that there is more to using a language than that. Sure your pronunciation shouldn't interfere with someone understanding you but beyond that it's about what you can do with the language -request, express emotion and needs, tell what happened, counsel, persuade, describe, etc. and how well or to what degree of sophistication. Keep this comparison in mind. As I have heard, Henry Kissinger the former Secretary of State, whose first language is German, would be rated a 4+ on the ILR scale. If it weren't for his heavy accent he would be considered as a native English speaker. Despite the accent, look at what he can do with the language. That in itself is quite an accomplishment that we can all aspire to.