The words come out of your mouth in the way that you want them to, but they are not being understood the way that you mean them to be by the audience you are speaking to. You may want to try to change the way that you speak. Of course as far as the real world application goes, this does not mean to literally change the way that you pronounce words, but to change your speech tendencies so that they will be easier for others to grasp, particularly for those that are not as familiar with you, or are not friends with you.
This interpretation does not necessarily have to relate to speaking either. It could mean that you are having trouble expressing yourself in an emotional sense as well. You are not able to convey your true feelings about anyone and feel stunted in that regard. There are ways that this can be helped and you should be able to, after some practice, be a lot better at telling people the way that you really feel about things. A therapist would be an excellent person to see if this is a real world problem for you. Even an understanding friend would be a good choice. Someone that you know with a very patient attitude would be a great consultant to you if you feel this way.
The accent can be seen usually two different ways culturally. In one sense it can make one very popular and make them likable and worthy of notice all because of the fact that their accent makes them stand out. Not to mention that it can make members of the opposite sex attracted to them. However, if the accent is seen as ugly or unattractive, it can make them stand out in the opposite way. They suddenly go from fine looking and amiable to completely off-putting. Having an unattractive accent can mean the difference between having friends in a strange land and being completely shunned. It is because of this high level of relevance to your daily life that these situations can manifest themselves as dreams too.
If you dream that you have an accent which makes people attracted to you and garners you friends and attention, this usually means you have an inflated sense of ego. This does not indicate that this ego is something that you have been struggling with your entire life, but it does give off the idea that some small ego boost has occurred recently which has caused you to act out of character in a fashion which is negative to your overall development. Remember, social success is always temporary.
Dreaming about having a negative accent or a voice which turns people away from you indicates a diminished sense of self esteem. A dream like this might occur if you have recently moved, or been forced to make friends with an unfamiliar group. Thrust into this situation, you would definitely find yourself to be a bit out of your element and even afraid.