Er du i gang med at skrive den sidste rettelse, eller kan vi gå videre nu?

It is a very common Danish way to say that someone is in the middle of doing something.

So:

Er du i gang med at skrive ...?
= Are you in the process of writing ...? / Are you still working on writing ...?

The fixed expression is:

• være i gang med noget = to be busy with something
• være i gang med at + infinitive = to be in the middle of doing something

So i gang med at skrive means busy writing or currently writing.

Because this is a yes/no question, Danish normally puts the verb first.

• Du er i gang med at skrive ... = You are in the middle of writing ...
• Er du i gang med at skrive ...? = Are you in the middle of writing ...?

This is standard Danish word order for yes/no questions, just like English often uses inversion:

• You are ready.
• Are you ready?

Here at skrive is the infinitive, meaning to write.

After i gang med, Danish often uses:

• i gang med + noun
• i gang med at + infinitive

Examples:

• Jeg er i gang med arbejdet. = I am busy with the work.
• Jeg er i gang med at arbejde. = I am working / I am in the middle of working.

So in your sentence:

• i gang med at skrive = in the middle of writing

Literally, it means the last correction or the final correction/edit.

Breaking it down:

• den = the
• sidste = last / final
• rettelse = correction, revision, edit

In context, it probably means the final change that still needs to be made before moving on.

Depending on context, English might translate it as:

• the last correction
• the final edit
• the final revision

Because Danish usually uses a double definite structure when an adjective comes before a definite noun.

So instead of just saying the final correction with one marker of definiteness, Danish often uses:

• den
  • adjective + noun

Here:

• en rettelse = a correction
• rettelsen = the correction
• den sidste rettelse = the last/final correction

This is very common:

• den store bil = the big car
• det nye hus = the new house
• de gamle bøger = the old books

So den sidste rettelse is the normal form.

They are related, but they do different jobs.

• sidste = last/final as an adjective

  • den sidste rettelse = the last correction

• sidst = last / most recently as an adverb

  • Jeg så ham sidst i går. = I saw him last yesterday / most recently yesterday.

In your sentence, sidste describes the noun rettelse, so it has to be the adjective form.

Not only, but that is a very common meaning.

Rettelse can mean:

• a correction in a text
• a revision or edit
• a correction of a mistake
• sometimes a formal correction or amendment

In this sentence, because of skrive and the general context, it most likely means an edit/correction to something being written.

A learner might also compare it with:

• ændring = change
• rettelse = correction

A rettelse usually suggests that something was wrong or needed fixing, while ændring is a more general change.

Literally:

• eller = or
• kan vi = can we
• gå videre = go further / move on
• nu = now

So the whole part means:

or can we move on now?

In natural English, gå videre often means:

• move on
• continue
• proceed

It does not necessarily mean physically walking somewhere. Here it means continue to the next step/topic/task.

Yes, very much so.

at gå videre often means:

• to move on
• to proceed
• to continue to the next stage

Examples:

• Lad os gå videre. = Let’s move on.
• Vi kan ikke gå videre endnu. = We can’t proceed yet.
• Skal vi gå videre til næste punkt? = Shall we move on to the next point?

So in your sentence, it means continue now that this last correction may be finished.

Putting nu at the end is very natural in Danish. It often gives the sense of now, at this point.

So:

kan vi gå videre nu?
= can we move on now?

The placement is normal and idiomatic. Danish often puts short time words like nu later in the sentence.

It is neutral, everyday Danish. It would fit well in:

• a workplace
• a group project
• editing/writing situations
• casual professional conversation

It is not slang, and it is not especially formal. It sounds like a normal, polite question.

Yes, if translated word-for-word, it can sound slightly unusual in English, because English does not always say write a correction in the same way.

Danish can naturally say:

• skrive en rettelse
• lave en rettelse
• rette noget

Depending on context, English might prefer:

• finish the last edit
• make the final correction
• write the final revision
• fix the last thing

So the Danish is fine, but the most natural English translation may depend on what is being corrected.

Yes. Here are a few natural alternatives:

• Er du ved at skrive den sidste rettelse, eller kan vi gå videre nu?
• Er du færdig med den sidste rettelse, eller skal du lige skrive den først?
• Skriver du stadig på den sidste rettelse, eller kan vi gå videre nu?

These are slightly different in nuance:

• er du i gang med at ... = are you in the middle of ...
• er du ved at ... = are you doing / in the process of ...
• skriver du stadig ... = are you still writing ...
• er du færdig med ... = are you finished with ...

The speaker is asking which of two situations is true:

1. Are you still working on the final correction?
2. Or are we ready to continue now?

So the sentence suggests a small decision point: do we wait, or can we proceed?

That is why eller is important: it sets up the alternative between still working and ready to move on.