Hun er den kollega, jeg arbejder sammen med, når vi retter dokumenter.

Because kollega is a common-gender noun in Danish: en kollega. Common-gender nouns take den in this kind of definite phrase.

• en kollega → den kollega
• et dokument → det dokument

So det kollega would be wrong.

Danish often uses den/det/de + noun when the noun is followed by a clause that identifies it more precisely.

Here, jeg arbejder sammen med tells you which colleague is meant, so den kollega is very natural.

You may compare:

• kollegaen = the colleague
• den kollega, jeg arbejder sammen med = the colleague I work with

So the structure helps set up the relative clause that follows.

In Danish, the relative word is often left out when it is understood from the context.

So:

• den kollega, jeg arbejder sammen med
• den kollega, som jeg arbejder sammen med

are both correct.

The version without som is very common and natural.

Because arbejder sammen med is the full expression: to work together with someone.

The person being referred to is den kollega, and that person is understood as the object of med. Since the noun has been moved to the front as the thing being described, the preposition stays behind:

• jeg arbejder sammen med hende
• den kollega, jeg arbejder sammen med

This is very similar to natural English:

• the colleague I work with

arbejde sammen med emphasizes working together / collaborating with someone.

By contrast, arbejde med often means work on, deal with, or work with in a broader sense. It does not stress cooperation as clearly.

So:

• arbejde sammen med en kollega = collaborate with a colleague
• arbejde med dokumenter = work on documents

In this sentence, sammen makes it clear that the colleague is a partner in the task.

Når is used for something that happens repeatedly, generally, or whenever the situation occurs.

Here the idea is not one single past event, but a recurring work situation: whenever we are correcting documents, she is the colleague I work with.

That is why når fits well.

They mean different things:

• når = when / whenever in repeated or general situations
• da = when for one specific event, usually in the past
• mens = while, focusing on two actions happening at the same time

So in this sentence:

• når vi retter dokumenter = when/whenever we correct documents

If you used da, it would suggest one particular past occasion. If you used mens, the meaning would shift more toward while we are correcting documents.

Because these are subordinate clauses, not main clauses.

In Danish main clauses, the finite verb usually comes in second position. But in subordinate clauses, the normal order is typically:

subject + verb

So you get:

• jeg arbejder sammen med
• når vi retter dokumenter

That is why there is no inversion here.

Here retter means correct, revise, or edit documents.

The verb rette is very common in Danish and often means fixing mistakes in writing, schoolwork, or text.

Depending on context, retter dokumenter could mean:

• correcting errors
• proofreading
• revising text
• editing documents

So it is a normal everyday choice here.

They mark clause boundaries.

The sentence contains more than one clause:

• main clause: Hun er den kollega
• relative clause: jeg arbejder sammen med
• time clause: når vi retter dokumenter

The commas help show where one clause ends and another begins.

You should also know that Danish comma usage has some variation, because more than one accepted comma style exists. But the punctuation in this sentence is completely standard and easy to recognize.