Writing a characterization is part of many advanced English courses. The idea is to look closely and systematically at a character that appears in a novel, short story or any other kind of fictional text.
Depending on the focus of the task you’re given, your text should describe this character and/or analyze techniques used by the author to create this impression.
The exact format of a characterization obviously depends on your course and your teacher, professor, etc.; I present what I think is a good general way to write a text like this.
On my channel you will find similar videos looking at how to analyze a speech, how to write a summary etc. - check out the playlist.
Let me know if you have comments or questions!