Entity modelling is saying what is and doing so purposefully. It is a particular formal technique for the representation of conceptual models; its practitioners represent types of entity as labelled boxes and relationships as annotated connections between boxes. There is no standard notation - different authors use different diagramming styles and models are variously known as entity models, entity-relationship (ER) models or entity relationship attribute (ERA) models. This site promotes a notation that is a refinement of the Barker-Ellis notation.
Entity modelling is said to be an abstract way to describe a database (more specifically the structure of a database), and so it is, but its utility goes further than this as discussed here.