A Leave Year is the period of time that your Leave spans, this is a 12 month period and can start at any time in the year. Generally, Leave Years run from January to December, but yours may start at a different time, depending on policy.
You may be required to change this at some point, e.g. from January to December to run from May to April. Leave Years are attached to Work Profiles, so all users within a Work Profile will have the same Leave Start Month. It's possible to change this for the entire organisation or certain Work Profiles.
If you want to change this for specific Work Profiles, go to Leave > Admin & Config > General Settings > Leave Start Month
Untick the box 'Enforce consistent Leave Start Month' then click Save.
Then, go to Leave > Admin & Config > Work Profiles, select the Work Profile you want to edit and in the Leave Settings tab you will be able to select a new Leave Start Month.
Once you save this, a dialog will pop up with a warning. You'll need to go to the Adjust Allowance Range tool to ensure your employees' allowances are updated correctly following the change. Click OK and you'll be taken to the Adjust Allowance Range tool.
For each Team and Work Profile, you will be able to see a view of the previous year's balance and the new year's balance. Check these are correct and then click Save Changes.
For more information on the Adjust Allowance Range tool, take a look at the article here.