Questions & Answers about Hún kann að spila á gítar.
Because hún is the subject form of she.
In this sentence, she is the person doing the action, so Icelandic uses the nominative form:
- hún = she
- hana = her
- henni = to her / for her
So Hún kann að spila á gítar means She knows how to play the guitar or She can play guitar, and hún is correct because she is the subject.
Here kann means knows how to or is able to because of learned skill.
That is important, because Icelandic often distinguishes between:
- kunna = to know how, to have learned a skill
- geta = can, be able to, be possible
So in this sentence, kann suggests that she has learned the skill of playing guitar.
For example:
- Hún kann að synda = She knows how to swim.
- Hún getur synt = She is able to swim / she can swim (in this situation).
In everyday English, both may translate as can, but Icelandic often keeps that distinction clearer.