Article snapshot taken from Wikipedia with creative commons attribution-sharealike license.
Give it a read and then ask your questions in the chat.
We can research this topic together.
UML is unique in that it has a standard data representation. This representation is called the metamodel.
The meta-model is a description of UML
in
UML. It describes the objects, attributes, and
relationships necessary to represent the concepts of UML within a software application.
UML class metamodel defines what a UML class is.
Bibliography
Zhao L., Siau K. (2003). Meta-Model Based Information Mediation // Idea Group Inc., p. 8 – 9.
Muller P.A. (1997). Instant UML // Wrox Press, p. 73–94