She kinda looks like she's wearing body-paint here.
…Wait a minute. I just realized that since she made her dress out of her own ice, that technically means she's walking around naked, at least if she's not wearing anything else underneath. But since she's pretty much immune to the cold, she wouldn't really need to.

her powers are weird though
she can make ice, but at the same time, can make clothes

its been confirmed in the last two frozen shorts
so essentially, it's like piccolo's clothes beam