This emoji represents not only children's sledding but also Winter Olympic sports like luge or skeleton, where athletes race down a track at very high speeds. Thus, it can express both fun and thrilling speed.

Because a sled goes down a hill at high speed, it can be used positively to mean 'things are progressing quickly,' or sometimes metaphorically to describe a situation worsening, like 'sliding out of control.' It's an emoji that can be used in fun ways depending on the context.