Hún sendi rangt bréf óvart.

The sentence is built like this:

• Hún = subject
• sendi = verb
• rangt bréf = direct object
• óvart = adverb

So the overall pattern is:

Subject + verb + object + adverb

A very literal breakdown is:

• Hún = she
• sendi = sent
• rangt bréf = wrong letter
• óvart = by accident / accidentally

Yes. Sendi is the past tense of að senda, meaning to send.

So:

• hún sendi = she sent
• hún sendir = she sends / is sending

In this sentence, sendi clearly shows that the action happened in the past.

Here, rangt is an adjective modifying bréf.

It means wrong in the sense of the wrong letter, not sent wrongly.

That matters because rangt can also be an adverb in other sentences. For example:

• Hún skrifaði nafnið rangt. = She wrote the name wrong / incorrectly.

But in Hún sendi rangt bréf óvart, the word rangt comes directly before the noun bréf, so it is understood as an adjective: wrong letter.

Because bréf is a neuter singular noun, and the adjective has to agree with it.

In Icelandic, adjectives change form to match the noun’s:

• gender
• number
• case

Here:

• bréf is neuter
• it is singular
• it is the direct object, so it is in the accusative
• the adjective therefore takes the matching form rangt

So:

• masculine might look different
• feminine might look different
• neuter singular here is rangt

For comparison:

• rangan pakka = wrong package/parcels item? masculine
• ranga bók = wrong book
• rangt bréf = wrong letter

Bréf is the direct object of sendi, so it is in the accusative case.

The reason it does not look different is that many neuter singular nouns in Icelandic have the same form in nominative and accusative.

So although bréf is accusative here, it still looks like bréf.

This is very common and can be confusing at first, because the case is there grammatically even when the form does not visibly change.

Icelandic normally has no separate indefinite article like English a/an.

So:

• bréf can mean a letter or just letter, depending on context

For the definite article, Icelandic usually adds it to the end of the noun:

• bréf = a letter / letter
• bréfið = the letter

So rangt bréf is naturally understood as a wrong letter or the wrong kind of letter, depending on context.

You would usually say:

ranga bréfið

Here is what changes:

• the noun becomes definite: bréf → bréfið
• the adjective changes to the weak form: rangt → ranga

So:

• rangt bréf = a wrong letter
• ranga bréfið = the wrong letter

That adjective change is normal in Icelandic when a noun becomes definite.

Óvart means by accident or accidentally.

It is an adverb, and it does not change form.

In this sentence, it tells you that the sending was not intentional:

• Hún sendi rangt bréf óvart. = She sent the wrong letter by accident.

A useful pattern to remember is:

• gera eitthvað óvart = do something by accident

Yes. Icelandic word order has some flexibility, and óvart can be placed in different spots.

For example, these are all possible:

• Hún sendi rangt bréf óvart.
• Hún sendi óvart rangt bréf.
• Óvart sendi hún rangt bréf.

The most neutral options are usually the first two. Fronting óvart gives it more emphasis.

One important rule is that Icelandic main clauses normally follow a verb-second pattern. So if you move óvart to the front, the verb still comes second:

• Óvart sendi hún rangt bréf.

not

• Óvart hún sendi rangt bréf

In ordinary modern Icelandic, hún is the feminine third-person singular pronoun, so yes, it means she.

At the start of the sentence it is capitalized simply because it is the first word:

• Hún at the beginning
• hún in the middle of a sentence

So there is nothing special about the capital letter here beyond normal spelling.

The main change would be the verb:

• past: Hún sendi rangt bréf óvart.
• present: Hún sendir rangt bréf óvart.

So:

• sendi = sent
• sendir = sends

The rest of the sentence can stay the same.