What does it mean to dream about a "good" witch?
A friend had a dream in which a "good" witch offered her protection. She was a witch yet she was wearing white.
Contrary to "Christian" dogma and Hollywood hype the word witch comes from the Anglo-Saxon root meaning alive/living/lively.
The language is of little importance. What matters is the meaning. Thus your friend may have dreamed of an energetic entity offering her protection and interpreted it in her mind as good witch. She could also have perceived this as angel, spirit, spirit guide, guardian angel/spirit, good fairy, fairy godmother etc.