Universe is an entity which is difficult to comprehend. So for an easy understanding here is a pyramid which describes the physical system, giving a clear understanding.
Level 1- It consist of basic entity like Space, Time, Energy, Chance, Information
Level 2- Space-time continuum, Action, Uncertainty, Irreversibility
Level 3- Mass, Hierarchy, Statistical Sate
Level 4- Unified field, Cosmology
Level 5- Physical universe itself.
There are complicated terms which I will explain in my next post when I will have ample time.