In this recipe, you created an empty GameObject called water-block-container to act as a container for a WaterBlock. By adding a WaterBlock to this parent GameObject, you made it possible to make copies and move them in the scene so that the animations were relative to the location of each parent (container) GameObject.
By adding a Box Collider and setting the layer of WaterBlock to Ground, you enabled the player's character to walk on these blocks.
You created a two-state Animator Controller state machine. Each state was an Animation Clip. The Up state is for WaterBlock at normal height (Y = 0), while the Down state is for WaterBlock further down the screen (Y = -5). You created a Transition from the Water Block Up state to its Down state that will take place when Animator Controller receives a Fall Trigger message.
After that, you added a second Box Collider 2D with a Trigger to WaterBlock so that...