causing terror, excitement, or astonishment

"Hair-raising" means "frightening," "shocking," or "stunning". It relates to the physical sensation of the hair on the back of your neck "raising" like with goosebumps. In more poetic uses, hair-raising relates to "amazing" or "astonishing" actions.

It means extremely frightening but often exciting, like a hair-raising story, or when you take roller coaster, it'll be a hair-raising experience. BTW, my network is not well, some responses may not be in time.