Very simply meta-data is like a label or a name on data-file . You can think of it as the description, annotation and organization of data. It varies as much as data does . It can be as simple as a readme file or as complex as a data dictory.
Research Meta-data is part of the data management process and is generally descriptive . However all data-sets should have meta-data with elements of all the types above. There are different meta-standards and they vary according to discipline, type of data and the extent to which it is intended to be preserved over the long term.Meta-data describe your data and your project files. It is a description of what you have done , the way you have done it and how your did it. In other words, context, background and operating procedures.
This file is about as simple as you can get but if you want to just try out what a meta-data file would look like, use it. The better approach is to decide on meta-data during data management planning in the research development stage. There is also a very good templates for specific types of data so email the librarian with your data type and you will get a template back.
if you really want to work with metadata you need to get familiar with schemas. These are the structured and organized ways in which data is presented in a specific sciences or sub-field of a science or a social discipline. Its the language of the researchers .