Hún ætlaði að fara snemma að sofa, en endaði á að lesa aðeins meira.

Ætlaði is the past tense, 3rd person singular, of ætla.

So with hún, it means she intended, she was going to, or she planned to, depending on context. The sentence is talking about what she meant to do, so the past tense fits naturally.

After ætla, Icelandic normally uses að + infinitive.

So:

• ætla að fara = intend to go
• ætla að lesa = intend to read

Here, ætlaði að fara means intended to go / was going to go.

That að is the infinitive marker, similar to English to.

They belong to two different infinitives:

• ætlaði að fara = intended to go
• fara að sofa = go to sleep / go to bed

So the first að goes with fara, and the second að goes with sofa.

This can look strange to English speakers at first, but it is completely normal Icelandic.

Fara að sofa literally means go to sleep, but in many contexts it is used the way English uses go to bed.

So:

• fara að sofa snemma or fara snemma að sofa = go to bed early

It is a very common everyday expression.

Snemma is an adverb meaning early. It describes when she was going to go to bed.

In this sentence, fara snemma að sofa is a natural word order. English speakers may want to match English word order exactly, but Icelandic adverb placement is somewhat flexible. This position sounds normal and idiomatic.

So the phrase means:

• fara snemma að sofa = go to bed early

not something like go early to sleep in a literal word-by-word sense.

En means but.

It connects the two parts of the sentence:

• she intended to go to bed early,
• but she ended up reading a bit more.

It works very much like English but in this kind of contrast.

Because the subject is the same in both parts of the sentence.

Icelandic often leaves out the repeated subject in coordinated clauses when it is easy to understand:

• Hún ætlaði ... , en endaði ...

This still clearly means:

• She intended ..., but she ended up ...

You could repeat hún for emphasis or clarity, but it is not necessary here.

Enda á að + infinitive is an idiomatic Icelandic pattern meaning end up doing something.

So:

• enda á að lesa = end up reading
• enda á að fara = end up going

In your sentence, endaði á að lesa means ended up reading.

The á is part of this construction. It is best to learn enda á að as a set phrase rather than trying to translate each word separately.

Because after endaði á að, Icelandic uses að + infinitive.

So:

• endaði carries the past tense
• lesa stays in the infinitive

That is why Icelandic says endaði á að lesa, not a past-tense form of lesa there.

This is similar to English ended up reading, where the past meaning comes from ended up, not from changing the second verb into a separate finite verb.

Aðeins often means a little, a bit, or just.
Meira means more.

Together, aðeins meira means:

• a little more
• a bit more
• just a little more

In context, it suggests she read a bit longer than she had planned.

Meira is the comparative form meaning more. Here it is being used without a noun, in an adverb-like way: a bit more.

So aðeins meira does not mean more of a specific stated noun such as more pages or more time. It is more general, like English a little more.

That makes it very natural in sentences about continuing an action a bit longer:

• lesa aðeins meira = read a little more