What is 'Expire Carry Forwarded Leaves (Days)' in the Leave Policy

Hi community, referring to the below screenshot, does anyone know what does ‘Expire Carry Forwarded Leaves (Days)’ do?

If a Leave Type is carry forwarded, but there is an expiry to use those carry-forwarded leaves, then you can mention days in which it expires in this field.

You mean if that leave expires, I can carry it over to next year?
For example
I have 30 days during a whole year and 10 days of expired vacations,
Next year I will have 40 days?

I need an example to understand it :pray: