Object Diagram is a visual representation of the objects and their relationships in a system. It is used to show the structure of a system and how the objects interact with each other. It is a type of UML diagram that is used to represent the static view of an object-oriented system
From Wikipedia
In object-oriented programming, an object diagram in the Unified Modeling Language (UML) is a diagram that shows a complete or partial view of the structure of a modeled system at a specific time.