Lots of crazy things go down in The Scarlet Letter – things like eyes that glow red, meteors in the shape of an “A,” witches that go riding their broomsticks. In many ways we readers learn to understand these events as being part of a fable or (dark) fairy tale. We’re not so much concerned with whether these supernatural occurrences are real or not, but we know they are telling us something important about the characters and the secrets they keep.
In the world of this story, the supernatural is anything that cannot be explained.
Pearl’s eerie intelligence and elfish ways are just a product of being excluded from society. She just doesn’t have any social skills.