Using Kassets' ScriptableObject Instances
Usage on MonoBehavior Script
Create a MonoBehavior Script and add Kassets' instance as a serialized field.
Player.cs :

HealthBarUI.cs :

Drag and drop PlayerHealth (FloatVariable) to Player's Health field :

Drag and drop PlayerHealth (FloatVariable) to HealthBarUI's Health field :

From example above, Player component's field Health and HealthBarUI component's field Health both refer to the same FloatVariable ScriptableObject instance PlayerHealth. Since both component refer to the same variable instance, the float value they refer to is shared. Each component then manage their own need with the value without any coupling between components. I.e. HealthBarUI doesn't have to request the Health value to Player component and Player component can manage its own Health without the need to distribute its value to other components.
Usage on UnityEvents
Kassets’s instance is a ScriptableObject asset. It can be referenced to UnityEvent via Inspector. You can aslo use dynamic method call on UnityEvent to pass a parameter.

