Whether terrazzo flooring is slippery will be up to you. There are things you can add to the flooring, so it won’t be slippery. The type of sealer you use after you’ve polished the floor is important. Check the manufacturer’s label for details indicating if a floor is non-slippery when wet.
Shiny floors look slippery, but it’s the sealer that makes them slippery. If you don’t want to apply a sealer, use lower grit levels to create a slip-resistant floor.