If you dream about your arm being injured, then it could show various things such as you dont think you belong in society, or you dont know how to fit in it, or you simply feel unneeded by those you love. The arm could also signify the fact that you wish to do more than you can, especially if you see more than two arms. Perhaps you have too many things to do.
Arm dream meaning
Read more about dreaming of Arm in other dream meanings interpretations.