I tend to remember "pa sig" as "on her"
The woman has on her a dress or the woman has a dress on her.
Little bit funny in English, but meaning is still the same.
Im getting "kvinnan bär en klänning" is correct. I wish it wouldnt introduce random words out of the blue. I get it may also be correct, but a little explanation would be nice.
I couldn't agree more. As it is, any accepted answer can get shown to users as 'another correct answer'. That makes it much harder for us to choose what answers should be accepted.
I once encountered a sentence that, instead of saying for example har på sig, it said something like har på dig. What is the difference between using sig and another third person or even first person pronoun (mig, oss, den, det, er, honom etc)?
So is it always sig when referring to hon, han, de, det, den?... or can henne, honom, dem, det, det also be used respectively, depending on the context?
For all third person people, it's sig. The verb (att ha på sig) requires the pronoun here to refer back to the subject, so it has to be "sig" and not henne/honom/dem etc.
Yes, that's another accepted answer. (If you do stress en like that though, you should translate it back as 'one dress' – though I get that you just wanted to highlight the difference).