Steeping is "sitting"
Aka after you get your juice you let it sit for a while.
It will change flavor and sometimes color. Most juices improve/change for the best over time. Some turn to worse. It all depends on a particular juice.
Letting your new juice steep is especially a good idea if you ordered a "Oh so amazing everyone raves about juice" but you can not understand why?
Just let it sit and try later on