Ausan liggur enn í pottinum, því ég gleymdi að setja hana í vaskinn.

Ausan is the definite form: the ladle.

The base noun is ausa, a feminine noun. In Icelandic, the definite article is usually attached to the end of the noun instead of being a separate word like English the.

So here:

• ausa = a ladle
• ausan = the ladle

Because it is the subject of the sentence, it is in the nominative singular definite form.

Icelandic often prefers a position verb where English would simply use is.

• liggja = to lie
• sitja = to sit
• standa = to stand

So Ausan liggur í pottinum literally means The ladle lies in the pot, but in natural English we would often just say The ladle is in the pot.

This is very common in Icelandic. Objects are often described by how they are positioned, not just by their existence in a place.

Here enn means still.

So:

• Ausan liggur enn í pottinum = The ladle is still in the pot

A useful extra point:

• in affirmative statements, enn often means still
• in negative sentences or questions, it can often mean yet

For example:

• Hún er enn hér = She is still here
• Hún er ekki komin enn = She hasn’t arrived yet

This is a very important Icelandic pattern.

With prepositions like í:

• dative is used for location: being in something
• accusative is used for motion toward / into something

So in this sentence:

• í pottinum = in the pot → location, so dative
• í vaskinn = into the sink → movement/destination, so accusative

That is why the forms are different.

Their dictionary forms are:

• pottur = pot
• vaskur = sink

In the sentence, they appear in definite case forms:

• pottinum = the pot in dative singular
• vaskinn = the sink in accusative singular

Again, the article is attached to the noun:

• pottur → pottinum
• vaskur → vaskinn

So English uses the pot / the sink, but Icelandic builds the into the word itself.

Hana means her / it in the accusative, and it refers back to ausan.

Since ausa is a feminine noun, the pronoun must also be feminine.

Here hana means it, not her in the human sense.

Why accusative? Because it is the direct object of setja:

• setja hana í vaskinn = put it in the sink

So the grammar is:

• feminine noun: ausa
• feminine pronoun: hún / hana
• here, object form: hana

Gleymdi is the past tense of gleyma, meaning forgot.

Then að setja is the infinitive phrase to put.

So:

• ég gleymdi að setja hana í vaskinn = I forgot to put it in the sink

This is a very common structure in Icelandic:

• gleyma að + infinitive = forget to do something

For example:

• Ég gleymdi að hringja = I forgot to call
• Hann gleymdi að loka glugganum = He forgot to close the window

Because að is the normal infinitive marker, like English to.

So:

• setja = put
• að setja = to put

After many verbs, Icelandic uses að + infinitive:

• ætla að fara = intend to go
• reyna að skilja = try to understand
• gleyma að setja = forget to put

So here að is not a separate word with a special meaning like that; it is just marking the infinitive.

In this sentence, því is being used as a conjunction meaning because / since.

So:

• Ausan liggur enn í pottinum, því ég gleymdi að setja hana í vaskinn.
• The ladle is still in the pot, because I forgot to put it in the sink.

This can confuse learners because því has several uses in Icelandic. But here it is simply introducing the reason.

In everyday speech, you will also often hear:

• af því að = because

So the sentence could also be expressed with af því að, though því is perfectly natural.

Because því here is a conjunction, not a fronted adverb.

After a conjunction like því meaning because, the clause keeps normal order:

• ég gleymdi

So:

• því ég gleymdi... = because I forgot...

If you put some other element first in a main clause, Icelandic often uses inversion:

• Í gær gleymdi ég... = Yesterday I forgot...

But that is a different pattern. In your sentence, því simply introduces the reason clause, so ég gleymdi is the expected order.