That’s what the person you’re replying to means as well, five weeks or 25 workdays. I think all or at least most of the EU have more than 15 days minimum mandatory paid leave.

Well, isn't that normal? When you sign a 6 month contract that doesn't mean that you'll have to work for 180+ days either.

Assuming you’re working 5 days a week, 15 days is 3 workweeks.