There are two things, you and the not-you (=environment).
You have two interfaces with the universe, input (sensory) and output (action).
The two systems have their own dynamics and they are coupled.
For example, you may perceive water flowing from higher places to the ground.
You can learn from your observations, about the dynamics of the universe.
You can perturb the flow with your hand and perceive the change you incurred.
You can learn what changes your actions bring to the perceived universe.
