Complex sentence: The word "habilitation" can be used to describe the qualification itself, the process of earning that qualification or, incorrectly, the thesis written as part of that process (what is called "Habilitationsschrift" in German).
Split into simpler sentences: The word "habilitation" can be used to describe the qualification itself, or the process of earning that qualification. It is sometimes incorrectly used to refer to the thesis written as part of that process (what is called "Habilitationsschrift" in German).