Speaking of holiday, the Finnish way of calculating the annual holiday is really cryptic. The following example tries to explain how things go - but the system varies depending on whether you work for private company or state institution, and depending on the contract you're under.
First of all you have to earn your holiday before you can have them. In most of the cases you earn 2 holidays per month until you've worked in the same company and contract for one full "theoretic holiday year". After that you start earning 2,5 holidays per month. This theoretic holiday year is not a calendar year, but it lasts from April to March. So if you've started working in a company let's say from the beginning of November last year, you have earned 2*5=10 holidays, which you can keep during the summer holiday season (usually between May and September, in some places from June to September).
Let's clarify one term: by holiday we mean days when (according the law) you don't need to work, but you get full salary, and actually, you'll also get an extra bonus on top of the salary for each holiday - that's called holiday bonus.
Ok. Then comes the tricky part. If you have earned 10 holidays, it doesn't mean that you can be out of office for two full weeks - you need to count the Saturdays too, even though they are not normal working days. As an example, you could start your holiday on Monday. Until the end of the week you have spent 6 holidays (5 working days + extra Saturday), and you have 4 holidays left. So you should get back to office on the next week's Friday, that's when you've spent your 10 holidays. Luckily many employers may consider either giving some non-payed holidays, an option to balance with the flexible hours, or an option to swap your holiday bonus into holiday (i.e. then you don't take the bonus as money) - but this is something you definitely need to check from your employer, the practices vary a lot.
As said, this is a cryptic system and it varies depending on the contract, so you should definitely check and confirm your company's practices for example with your HR.