If the hose freezes, it becomes hard and brittle and can break.
To prevent freezing, you can put something in the hose to keep it from freezing. You can use a material like heat tape, which is a thin layer of insulation on the hose.
Another way to prevent the hose from freezing is to put the hose in warm water or hot water.
The hose can freeze in as little as 15 minutes at temperatures as low as 30 degrees F (0 degrees C).