Hún þurrkar framrúðuna og lagar svo spegilinn áður en hún tekur aftur um stýrið.

Because it is the definite singular accusative form of framrúða (windshield / windscreen).

• framrúða = a windshield
• framrúðan = the windshield (nominative)
• framrúðuna = the windshield (accusative)

Here it is the direct object of þurrkar (wipes), so Icelandic uses the accusative.

Spegilinn means the mirror, while spegill means a mirror.

The noun spegill is masculine, and in this sentence it is also a direct object, so it appears in the accusative definite singular:

• spegill = a mirror
• spegilinn = the mirror

So lagar spegilinn means adjusts/fixes the mirror.

The verb laga can mean fix, repair, put right, or adjust, depending on context.

In this sentence, with spegilinn (the mirror), the most natural meaning is adjusts the mirror rather than repairs the mirror.

So:

• lagar spegilinn = adjusts the mirror

Here svo means then or after that.

So the sequence is:

1. she wipes the windshield
2. then she adjusts the mirror
3. before she takes the wheel again

In other contexts, svo can also mean so, thus, or be part of other expressions, but here it is simply marking the next action.

Áður en means before.

It introduces a subordinate clause:

• áður en hún tekur aftur um stýrið = before she takes the wheel again

A useful way to remember it:

• áður = earlier / before
• en = than / when introducing this kind of clause

Together, áður en is a very common expression meaning before.

Because Icelandic normally states the subject again in the subordinate clause.

So:

• Hún þurrkar ... og lagar ...
• áður en hún tekur ...

Even though English sometimes also repeats she, learners may wonder whether Icelandic could leave it out. In normal Icelandic, you generally keep the subject explicit here.

Literally, tekur um stýrið means something like takes around the steering wheel or takes hold of the steering wheel.

But idiomatically, it means:

• takes the wheel
• grasps the steering wheel
• puts her hands back on the wheel

The important part is that taka um can mean take hold of / grasp something.

The preposition um usually takes the accusative.

So in:

• um stýrið

the noun stýri (steering wheel) is in the accusative definite singular.

Because stýri is a neuter noun, the nominative and accusative singular definite forms look the same:

• stýrið = the steering wheel

So even though you do not see a different ending here, it is still functioning as accusative after um.

Here aftur means again or back.

So:

• tekur aftur um stýrið = takes the wheel again / takes hold of the wheel again

It suggests that she had let go of the steering wheel for a moment and is now putting her hands back on it.

Because Icelandic often uses the present tense in the same kinds of situations English does:

• for a general description
• for habitual actions
• for narration of what is happening

So the sentence is simply describing the action in the present:

• þurrkar = wipes
• lagar = adjusts
• tekur = takes

Depending on context, English might translate this as she wipes... and then adjusts... before taking..., even if the broader situation is narrative.

No, it is quite natural.

The basic structure is:

• Hún þurrkar framrúðuna
• og lagar svo spegilinn

Here svo sits between the verb and the object, giving the sense then.

You could think of it as:

• and then adjusts the mirror

This placement is very common and natural in Icelandic.

Yes. Framrúða is a compound noun:

• fram = front
• rúða = pane / window

So framrúða is literally the front window, which is why it means windshield / windscreen.

Compound words are extremely common in Icelandic, and recognizing the parts can often help you remember vocabulary.

Yes, grammatically it could. The verb laga often means fix or repair.

But in this sentence, because the object is the mirror and the actions are part of driving preparation, the most natural interpretation is adjusts the mirror.

So context tells you which English translation is best.