Why is plural jackOR and not jackAR or jackER? I ask because of the rule for plural for en words. One-syllable words can take either -ar or -er, usually the former. en hund → hundar en färg → färger and -a → -or en kvinna → kvinnor en gata → gator
Is it exception or i didn't understand well? Tack :)
Here is a good link to a Wikipedia page on Swedish grammar that helped me with this and several other questions I had like this: https://en.wikipedia.org/wiki/Swedish_grammar
The short answer to your question is "Jacket used to be a feminine-gender noun." Thus, like kvinna and flicka (woman and girl), the plural is /-or.
Now, the next excellent question is: How do we know if a noun used to be feminine- or masculine-gender? The answer is "Usually, you don't." It's a memorization thing. =(
The definition of "several" is usually something like "more than a few but fewer than many". While it can mean "many" dialectally, it doesn't in any larger standard English, so we maintain the difference in the course since Swedish flera / många has the same distinction.