A financial year is a twelve-month duration used by businesses and other organizations to calculate their earnings and losses. The financial year is usually used in the industry compared with the calendar year.
In this option, you can close your financial year and review your previous financial years.
Here, you can see the list of your current and previous financial years.
In the
IS LOCKED section, You can see the status of your financial years.

If you want to close your financial year, just click on
CLOSE NOW.

You will see a popup showing your financial period. Enter your
Start Date[1], and
Closing Date from[2]. 
Finally, click on
UPDATE.