Ég klæði hana í pollagalla og vettlinga áður en hún fer út.

Because hana is the object of the verb klæða.

• hún = nominative, used for the subject
• hana = accusative, used for the direct object

In this sentence:

• Ég = the subject, the person doing the action
• klæði = dress
• hana = her, the person being dressed

So Icelandic uses the accusative here: Ég klæði hana ...

Later in the sentence, you get hún fer út, where hún is the subject of fer, so nominative is correct there.

Klæði is the 1st person singular present tense of the verb klæða.

So:

• að klæða = to dress, to clothe
• ég klæði = I dress

In this sentence, klæða means to dress someone / put clothes on someone.

A very useful contrast is:

• Ég klæði hana. = I dress her.
• Hún klæðir sig. = She gets dressed / dresses herself.

So Icelandic often distinguishes clearly between dressing someone else and dressing yourself.

Because Icelandic normally says klæða einhvern í eitthvað = dress someone in something.

So the pattern is:

• klæða + person + í + clothing

Examples:

• Ég klæði barnið í úlpu. = I dress the child in a coat.
• Hún klæðir sig í kjól. = She puts on a dress.

Even though í often means in, here it is part of the normal structure used with clothing.

They are in the accusative, because the preposition í often takes the accusative when it suggests movement into something or a change of state, and with klæða ... í ... that is the normal pattern.

So here:

• pollagalli → pollagalla (accusative singular)
• vettlingar / vettlingur → vettlinga (accusative plural)

The idea is not just location, but putting someone into those clothes.

Because a pollagalli is treated as one item of clothing, while vettlingar are naturally a plural item.

So:

• pollagalli = a rain suit / waterproof overall suit
• vettlingar = mittens

This is similar to English:

• a snowsuit
• mittens

Even if the suit has several parts, Icelandic treats pollagalli as one garment.

Pollagalli is a very common Icelandic word for a waterproof outdoor suit, especially for children.

It is the kind of outfit kids wear outside in wet weather, mud, slush, or light rain. In many contexts, it is better understood as:

• rain suit
• waterproof overalls
• waterproof outdoor suit

It is a very Icelandic everyday word because weather and outdoor play are such a big part of life in Iceland.

No. In this sentence, one í covers both nouns:

• í pollagalla og vettlinga

That means:

• in a rain suit and mittens

This is completely normal. Icelandic, like English, does not need to repeat the preposition if it applies to both items.

You could think of it as:

• í pollagalla og í vettlinga

but the second í is normally omitted.

Because fer is the present tense of fara and is used here in a very normal way after áður en.

• áður en = before
• hún fer út = she goes out

So the clause means before she goes outside.

In everyday Icelandic, áður en is commonly followed by the indicative in ordinary real situations like this.

Because in the clause hún fer út, hún is the subject of the verb fer.

Compare the two parts:

• Ég klæði hana ... → hana is the object
• ... áður en hún fer út → hún is the subject

So the pronoun changes case depending on its role in the sentence.

This is one of the most important things to notice in Icelandic: pronouns show grammatical function very clearly.

Here út means out / outside, with a sense of movement.

• fara út = to go out, go outside

By contrast:

• úti usually means outside in the sense of location

So:

• Hún fer út. = She goes outside.
• Hún er úti. = She is outside.

That is a very useful distinction in Icelandic:

• út = motion outward
• úti = being outside

Grammatically, it is in the present tense, but in context it very often sounds habitual or routine-like:

• Ég klæði hana ... áður en hún fer út.
• I dress her ... before she goes outside.

This could mean:

• something you usually do
• a regular part of getting ready
• what happens whenever she goes outside

Like English, Icelandic present tense can describe both a present action and a repeated routine, depending on context.

Yes. You can simply say:

• Ég klæði hana. = I dress her.

If you want to say what clothes she is being dressed in, you add í + clothing:

• Ég klæði hana í pollagalla.
• Ég klæði hana í vettlinga.
• Ég klæði hana í pollagalla og vettlinga.

So the longer sentence just gives more detail about what she is being dressed in.