What is Year-ending?

Legal Definition
Year-ending (or "12-months-ending") is a 12-month period used for financial and other seasonal reporting.

In the context of finance, "Year-ending" is often provided in monthly financial statements detailing the performance of a business entity. Providing current "Year-ending" results, as well as "Year-Ending" results for one or more past years as of the same date, allows owners, managers, investors, and other stakeholders to compare the company's current performance to past periods and annual figures.
-- Wikipedia