Thanks Mark, for going to the trouble of explaining all that. I do like to understand, if possible, what I am translating as well as upvoting :))

Wendy, I don't see a connection with the meaning of the term, i.e. fine for every day or daily fine. There is a lengthy article in Dutch about the 'dagboete' concept, see file:///C:/Users/Mark/Downloads/Dagboete-002-.pdf (p. 6 of the article) There is somewhat of an explanation in the paragraph: 'In Zweden ... van het feit.' Use Google Translate (Dutch -> English). In there is the key phrase, translated: 'Swedish law only generally mentions the features of the daily fine, such as the maximum number of 'days' and the maximum of the 'unit of day'. How the 'day unit' is calculated can (only) be found in detailed criminal procedure guidelines of the Public Prosecution Service.' So, day fine = number of days x unit per day, i.e. a way to calculate the fine.

Thanks Mark, reading on, I figured it must mean 'daily fine', but the term I find a bit strange - why 'daily'? Surely 'daily' means, every day?

Wendy, 'day fines' is a translation for 'dagboete'. A day fine or an income-related fine is a fine that depends on the income and any assets of the person who committed the offense or misdemeanor. See (Dutch): https://nl.wikipedia.org/wiki/Dagboete#:~:text=Een%20dagboete%20of%20een%20inkomensafhankelijke,of%20het%20delict%20heeft%20begaan.
Or see (English): https://en.wikipedia.org/wiki/Day-fine

Mark, do you know what a 'day fine' is?