Jeg sætter tallerkenerne i skabet, når opvaskemaskinen er færdig.

Because Danish usually puts the definite article at the end of the noun.

• tallerken = plate
• tallerkener = plates
• tallerkenerne = the plates

So -ne is the definite plural ending here.
This is one of the big differences from English: instead of a separate word like the, Danish often adds the definiteness directly to the noun.

For the same reason: skabet means the cupboard / the cabinet.

• et skab = a cupboard / a cabinet
• skabet = the cupboard / the cabinet

Here, skab is a neuter noun, so the definite singular ending is -et.

Because Danish normally uses a suffixed definite article.

So instead of saying something like the plates with a separate article, Danish usually says:

• tallerkenerne = the plates
• skabet = the cupboard

A separate definite word like de or det is usually used when there is also an adjective:

• tallerkenerne = the plates
• de rene tallerkener = the clean plates

Sætter is the present tense of at sætte, which often means to put, to set, or to place.

In this sentence, jeg sætter tallerkenerne i skabet means that the speaker is putting the plates into the cupboard.

Danish has several verbs that can translate as put in English, and the choice can depend on the object and how it is placed:

• sætte = put/set, often placing something in position
• stille = put/place, often for something standing upright
• lægge = lay/put, often for something lying flat

With everyday speech, there can be some overlap, and native speakers do not always make a sharp distinction in casual use.

I means in.

So:

• i skabet = in the cupboard

That is the natural preposition because the plates are going inside the cupboard, not on top of it.

Compare:

• i skabet = in the cupboard
• på skabet = on the cupboard

Yes. Ind i skabet is also possible, and it emphasizes movement into the cupboard.

Compare:

• Jeg sætter tallerkenerne i skabet. = I put the plates in the cupboard.
• Jeg sætter tallerkenerne ind i skabet. = I put the plates into the cupboard.

The version with just i is very common and sounds natural.

Because når is used for when in cases like repeated actions, general truths, and often future situations.

Here it means something like when the dishwasher is done.

Compare:

• når = when, whenever, once/when in the future
• da = when, but usually about a specific event in the past

So:

• Når opvaskemaskinen er færdig, ... = When the dishwasher is finished, ...
• Da opvaskemaskinen var færdig, ... = When the dishwasher was finished, ...

That is very normal in Danish.

Both parts of the sentence are in the present tense:

• jeg sætter
• opvaskemaskinen er færdig

But the meaning can still be future, especially with a time word like når.

English often does something similar:

• I’ll do it when it is ready

Notice that English also uses present tense in the when clause: when it is ready, not when it will be ready. Danish works similarly, and often the main clause can also stay in the present if it describes a routine or expected action.

Because after a subordinating conjunction like når, Danish uses normal subordinate clause word order:

• når opvaskemaskinen er færdig

That means subject + verb inside the subordinate clause.

The pattern is:

• når
  • subject + verb + rest

So:

• opvaskemaskinen = subject
• er = verb
• færdig = adjective

You do not invert the verb and subject after når.

Then Danish uses normal V2 word order in the main clause, so the finite verb comes before the subject:

• Når opvaskemaskinen er færdig, sætter jeg tallerkenerne i skabet.

Not:

• Når opvaskemaskinen er færdig, jeg sætter tallerkenerne i skabet.

This is a very important Danish pattern:

• If something other than the subject comes first, the verb usually comes next.

So:

• Jeg sætter tallerkenerne i skabet, når opvaskemaskinen er færdig.
• Når opvaskemaskinen er færdig, sætter jeg tallerkenerne i skabet.

Both are correct.

Færdig means finished, done, or ready depending on context.

In this sentence, opvaskemaskinen er færdig means the dishwasher has finished its cycle.

You will often see færdig in everyday Danish:

• Jeg er færdig. = I’m done.
• Er du færdig? = Are you finished?
• Maden er færdig. = The food is ready.

Because opvaskemaskinen is a singular common gender noun.

Adjectives after er often agree with the noun:

• common gender singular: færdig
• neuter singular: færdigt
• plural: færdige

Examples:

• Bilen er færdig. = The car is finished.
• Projektet er færdigt. = The project is finished.
• Tallerkenerne er færdige. = The plates are finished / ready.

Since opvaskemaskinen is singular and common gender, færdig is the correct form.

It is a compound noun:

• opvask = dishwashing / washing up
• maskine = machine
• opvaskemaskine = dishwasher
• opvaskemaskinen = the dishwasher

Danish uses compound nouns very freely, just like German and unlike English, where we often write them as separate words.

In standard written Danish, yes, a comma is normally written before a subordinate clause like the one introduced by når:

• Jeg sætter tallerkenerne i skabet, når opvaskemaskinen er færdig.

Danish comma rules can feel stricter than English comma rules in this kind of sentence, so this is a useful pattern to notice.

It can often be understood as a habitual or expected action, depending on context.

Because the sentence uses the present tense, it can sound like:

• something the speaker usually does
• something the speaker will do when that situation happens

So it may mean either:

• I put the plates in the cupboard when the dishwasher is done as a routine
  or
• I’ll put the plates in the cupboard when the dishwasher is done in a specific situation

Context tells you which meaning is intended.