Like dark matter, dark energy is one of the space anomalies we may never have a true answer for. What we do know is that dark energy is some form of unknown energy that affects our universe on incredibly large scales. Supernovae measurements help us find it, and helped us realize the universe was expanding at a much faster rate. Due to this discovery, we had answers for things beyond the normal forms of matter or energy that most understand.
Dark energy helped us explain cosmic events such as the Big Bang. We know it is the most likely reason the universe’s expansion has accelerated but we do not understand it all. Dark energy simply is too difficult to grasp for now, but that might not be the case for that much longer. As of 2020, research has been specifically aimed at looking further into dark energy. Perhaps we’ll know more about it one day.