Når vi besøger min søster, hjælper jeg med at folde tøjet og fylde skabet med bleer.

Når usually means when in the sense of whenever or at the times that.

So Når vi besøger min søster means When/Whenever we visit my sister.

A useful contrast:

• når = when, whenever, in general or in the future
• da = when, at one specific time in the past

So this sentence sounds like a habitual or general situation, not one single past event.

This is because Danish uses V2 word order in main clauses: the finite verb normally comes in second position.

The first part, Når vi besøger min søster, is a subordinate clause. When that whole clause comes first, it counts as the first element of the sentence. Then the finite verb in the main clause must come next:

• Når vi besøger min søster, hjælper jeg ...

Not:

• Når vi besøger min søster, jeg hjælper ...

This is very common in Danish.

The comma separates the subordinate clause from the main clause:

• Når vi besøger min søster = subordinate clause
• hjælper jeg med at folde tøjet ... = main clause

In Danish, commas are commonly used to mark this boundary.

In Danish, besøge is a normal transitive verb, so it takes a direct object:

• besøge min søster = visit my sister

You do not need a preposition here.

If you wanted to focus on going to her home, Danish could also say something like være hos min søster = be at my sister’s place, but that is a different expression.

hjælpe med at + infinitive is a very common Danish pattern meaning help with doing something or simply help to do something.

So:

• hjælper jeg med at folde tøjet
  = I help fold the clothes / I help with folding the clothes

The parts are:

• hjælper = help
• med = with
• at folde = to fold

In natural English, we often translate more simply, but in Danish this structure is very normal.

In Danish, when two infinitives are connected by og and depend on the same verb, you often use at only once:

• med at folde tøjet og fylde skabet

This means:

• to fold the clothes and fill the closet

The at applies to both folde and fylde.

You may sometimes see repeated at, but it is not necessary here.

tøj means clothes/clothing, and tøjet is the definite form: the clothes.

So:

• tøj = clothes / clothing
• tøjet = the clothes

In this sentence, tøjet sounds natural because it refers to specific clothes in the situation, not clothes in general.

Because they are being used differently:

• skabet = the closet / the cupboard
  This is a specific cupboard or closet known in the situation.
• bleer = diapers
  This is plural and indefinite, meaning diapers in general, not the diapers.

So:

• fylde skabet med bleer = fill the closet with diapers

If you said med bleerne, that would mean with the diapers, referring to specific diapers already known.

This follows a common pattern:

• fylde [something] med [something]
• fill [something] with [something]

So here:

• fylde = fill
• skabet = the closet/cupboard
• med bleer = with diapers

This structure is very productive in Danish:

• fylde flasken med vand = fill the bottle with water
• fylde tasken med bøger = fill the bag with books

Yes. Ble means diaper, and bleer is the plural diapers.

Examples:

• en ble = a diaper
• bleen = the diaper
• bleer = diapers
• bleerne = the diapers

This is the standard everyday word in Danish.

The present tense in Danish is often used for:

• general truths
• habitual actions
• repeated situations
• sometimes future meaning, depending on context

So this sentence suggests something like:

• When we visit my sister, I help...
• Whenever we visit my sister, I help...

It is not necessarily happening right this second; it describes what usually happens.

You would normally use da instead of når, and the verbs would usually be in the past tense:

• Da vi besøgte min søster, hjalp jeg med at folde tøjet og fylde skabet med bleer.

That means:

• When we visited my sister, I helped fold the clothes and fill the closet with diapers.

So the key contrast is:

• Når vi besøger ... = whenever / when we visit
• Da vi besøgte ... = when we visited, one specific time

A learner may notice that Danish pronunciation is often less obvious than the spelling.

Very roughly:

• besøger sounds something like beh-SOE-yer
  with the Danish ø sound, which does not exist exactly in English.

A few useful notes:

• ø is a rounded front vowel, somewhat like the vowel in French deux or German schön
• the g in besøger is not pronounced like a hard English g
• the ending -er in Danish verbs is often pronounced quite lightly

You do not need perfect pronunciation immediately, but it helps to listen to native audio because Danish sound changes are hard to guess from spelling alone.