Today at work they explained me and is interesting. It works like this:

• The Holiday earning time goes from 1st of september to 31st of august.
• The Spending time goes from 1st of september to new year of the next year, that is 1.2 year to spend.
• You can spend the vacations you are earning the same month, that is in september you can spend the vacations of september
• The number of vacations you have it in the pay slip

To put some numbers, one holiday year starts the 1st of september of 2022 and ends the 31st of august of 2023. The spending period of that holiday year goes from 1st of september of 2022 to 31st of december 2023.