Ég hoppa ekki eins hátt og hún.

Eins ... og is the Icelandic pattern for as ... as in comparisons.

So:

• eins hátt og hún = as high as she
• ekki eins hátt og hún = not as high as she

This is a very common structure:

• eins stór og = as big as
• eins fljótt og = as quickly as
• eins góður og = as good as

In your sentence, it compares how high I jump with how high she jumps.

In a simple main clause, Icelandic usually places the finite verb early in the sentence, and ekki often comes right after it.

So:

• Ég hoppa ekki ... = I do not jump ...

That word order is very natural in Icelandic.

Compare:

• Ég borða ekki kjöt. = I do not eat meat.
• Hún kemur ekki í dag. = She is not coming today.

English uses do not, but Icelandic usually just uses ekki with the verb form itself.

Here hátt is being used adverbially, meaning high in the sense of to a high height.

In English, we distinguish:

• adjective: high
• adverb: often also high

In Icelandic, the neuter singular form of many adjectives is often used adverbially:

• hár = high (masculine adjective form)
• hátt = high / highly, used adverbially here

So:

• að hoppa hátt = to jump high

This is why the sentence says eins hátt og hún.

Yes. Hoppa here is the 1st person singular present tense form:

• ég hoppa = I jump / I am jumping

This form is identical to the infinitive að hoppa in spelling, which can be confusing at first. But in the sentence, because it follows ég, it is clearly the present tense verb form.

Examples:

• að hoppa = to jump
• ég hoppa = I jump
• hún hoppar = she jumps

Because hún is the nominative form, and after og in this kind of comparison Icelandic often keeps the nominative pronoun.

So:

• hún = she
• hana = her

In this sentence, the comparison is understood as something like:

• Ég hoppa ekki eins hátt og hún (hoppar).
• I don’t jump as high as she (does).

Since hún is understood as the subject of the omitted verb hoppar, nominative hún is used.

This is similar to formal English than she rather than than her, though English usage is looser in everyday speech.

Yes, you can think of the sentence as having an omitted verb:

• Ég hoppa ekki eins hátt og hún (hoppar).

The final hoppar is normally left out because it is easy to understand from context.

This kind of omission is very common in Icelandic comparisons, just as in English:

• I don’t jump as high as she (does).

Yes, jafn ... og can also express as ... as.

So both of these can work:

• Ég hoppa ekki eins hátt og hún
• Ég hoppa ekki jafn hátt og hún

However, eins ... og is extremely common and very natural here.

A learner will often see both patterns, but eins ... og is one of the most basic and useful comparison structures to learn early.

Here og means as within the comparison structure eins ... og.

Normally:

• og = and

But in this pattern:

• eins ... og = as ... as

So you should understand the whole phrase together, not translate og by itself here.

If you remove the negation, you get:

• Ég hoppa eins hátt og hún. = I jump as high as she does.

With ekki, the meaning becomes:

• Ég hoppa ekki eins hátt og hún. = I do not jump as high as she does.

So the only difference is the addition of ekki, but that changes the comparison significantly.

A rough guide for an English speaker:

• Ég ≈ yegg with a softer y-like start
• hoppa ≈ HOP-pa
• ekki ≈ EHK-ki
• eins ≈ something like ayns
• hátt ≈ howht with a sharp t sound at the end
• og ≈ often like ohg or a softer reduced form in fast speech
• hún ≈ hoon

A few useful pronunciation notes:

• á is usually like ow in cow
• ú is like oo in food
• tt in Icelandic often has a distinctive pronunciation that may not sound exactly like plain English tt
• g in og may sound weaker than an English hard g, depending on speech

If you want to sound natural, focus especially on the rhythm of the comparison:

• Ég hoppa ekki eins hátt og hún.

Normally, no. Icelandic usually keeps subject pronouns, so:

• Ég hoppa ekki eins hátt og hún.

is the normal form.

Unlike languages such as Spanish or Italian, Icelandic generally does not omit the subject pronoun in ordinary sentences unless the context is very special, such as diaries, headings, or certain informal styles.

So for a learner, it is safest to include ég and hún when needed.

Here is a breakdown:

• Ég — pronoun, I
• hoppa — verb, jump
• ekki — adverb of negation, not
• eins — comparison word, part of eins ... og
• hátt — adjective form used adverbially, high
• og — comparison linker here, part of eins ... og
• hún — pronoun, she

So the overall structure is:

• subject + verb + negation + comparison phrase + pronoun

That makes it a very useful model sentence for learning Icelandic comparisons.