It is nothng but the information about information in database.... Is called metadata

I can tell you in case you are using Photoshop,open Bridge and select photo then look arround for metadata panel.click on it to expand.If you cant see metadata panel then go to Window-Metadata panel

No. Keywords are not called or known as Metadata in Java

"Metadata" defines the structure of the data stored.

Metadata is "data about data". There are two "metadata types;" structural metadata, about the design and specification of data structures or "data about the containers of data"; and descriptive metadata about individual instances of application data or the data content.