When you're animating, and you're making something move, right? If it has an accessory like this flower (The petals are the accessory and the stem is the moving object) The petals have to follow the stem moving, so when the stem moves, the petals follow. If the stem changes direction, the petals must too, but not directly when the stem does. The petals have to carry momentum to look real, meaning they stay a bit longer in that direction than the stem.

It's just an example and a thing for new animators to know. Have a good day! :)