Når vasken er færdig, lægger jeg vasketøjet i tørretumbleren.

Because Danish main clauses follow the verb-second rule. If something other than the subject comes first, the finite verb must come second.

Here, the subordinate clause Når vasken er færdig comes first, so the main clause is inverted:

• Når vasken er færdig, lægger jeg vasketøjet i tørretumbleren.

If the sentence started with the subject, it would be:

• Jeg lægger vasketøjet i tørretumbleren, når vasken er færdig.

So lægger jeg is normal Danish word order here.

Here når means when in the sense of something that regularly happens or is expected to happen.

• Når vasken er færdig = When the wash is finished

Danish hvis means if, for a real condition:

• Hvis vasken er færdig, lægger jeg vasketøjet i tørretumbleren
  = If the wash is finished, I put the laundry in the dryer

That sounds more conditional, as if you are checking whether it is finished.
With når, the idea is more natural for a routine or expected sequence.

It can mean different things depending on context, which is why learners often notice it.

Vasken can mean:

• the sink
• the wash / the laundry cycle / the washing

In this sentence, it clearly means the wash or the washing cycle, because it is followed by er færdig and then you move the laundry to the dryer.

So here vasken is not the sink.

Yes, but they refer to different things.

• vasken = the washing process / the wash / the load being washed
• vasketøjet = the laundry itself, the clothes and other items

So the sentence distinguishes between:

1. the washing being finished, and
2. the laundry being moved into the dryer

A rough distinction in English would be:

• When the wash is done, I put the laundry in the dryer.

In Danish, it is very common to say that something is finished using være + færdig.

• Vasken er færdig = The wash is finished / done

This is very natural Danish. English also often does something similar:

• The laundry is done
• The wash is finished

So this structure is not strange in Danish; it is one of the normal ways to express completion.

Because Danish forms compound nouns very freely, much more than English does.

• vaske = to wash
• tøj = clothes
• vasketøj = laundry / washed clothes / clothes for washing

Then the definite form is:

• vasketøjet = the laundry

This is very typical in Danish. English often writes similar ideas as separate words, but Danish usually joins them.

Because vasketøj is a collective noun. It refers to a group of items as one mass or category, much like English laundry.

So even though it refers to many pieces of clothing, the grammar is singular:

• Vasketøjet er vådt = The laundry is wet

This is similar to English the furniture, the luggage, or the laundry.

Danish often uses the definite form where English might or might not use the, especially when talking about familiar, specific things in everyday situations.

Here the speaker means:

• the particular wash that has just finished
• the laundry from that wash
• the dryer being used in this situation

So the definite forms are natural:

• vasken = the wash
• vasketøjet = the laundry
• tørretumbleren = the dryer / tumble dryer

This does not necessarily mean there is only one dryer in the world; it just means the relevant one in context.

Because Danish normally uses i for putting something into an enclosed machine or container.

• lægge noget i tørretumbleren = put something in the dryer
• lægge noget i vaskemaskinen = put something in the washing machine

This matches the basic physical idea of placing something inside.

Yes, putter is also possible in everyday Danish.

• lægger = lays/puts
• putter = puts

In this sentence, lægger sounds natural and standard.
Putter would sound a little more conversational:

• Når vasken er færdig, putter jeg vasketøjet i tørretumbleren.

Both are understandable, but lægger is a very common neutral choice.

Yes. Danish often uses the present tense for routines, habits, and even near-future actions, just like English sometimes does.

So this sentence can mean:

• something you usually do
• what you do in that kind of situation
• what you will do once the wash is done

The present tense is perfectly normal here.

Because Når vasken er færdig is a subordinate clause placed before the main clause.

Danish writing normally separates this kind of introductory clause with a comma:

• Når vasken er færdig, lægger jeg vasketøjet i tørretumbleren.

That comma helps mark the boundary between:

1. the time clause, and
2. the main statement

The dictionary form is at lægge, meaning to lay / put / place.

In the sentence:

• lægger = present tense

So:

• at lægge = to put
• jeg lægger = I put / I am putting

A learner should be careful not to confuse lægge with ligge:

• lægge = to put something somewhere
• ligge = to lie / be located

So here jeg lægger vasketøjet... means the speaker is actively placing it in the dryer.