Questions & Answers about Hun har på seg en rød genser.
Har på seg is a fixed expression that means is wearing.
- har = has
- på = on
- seg = herself / himself / themselves
So literally it is has on herself, which corresponds to is wearing in English.
If you say only Hun har en rød genser, it normally means She has a red sweater (owns it), not that she is wearing it right now. You need the full expression har på seg to talk about wearing.
Seg is a reflexive pronoun. It refers back to the subject hun.
- Hun har på seg … = She has on herself …
- Because the subject is 3rd person (hun/han/de), the reflexive form is seg.
For other persons, it changes:
- Jeg har på meg en rød genser. (I am wearing…)
- Du har på deg en rød genser. (You are wearing…)
- Vi har på oss en rød genser. (We are wearing…)
- Dere har på dere en rød genser. (You, plural, are wearing…)
- De har på seg en rød genser. (They are wearing…)
You would not say Hun har på henne en rød genser; henne would refer to another woman, not to hun herself.