Nach dem Auszug bleiben nur noch zwei Umzugskartons im Flur stehen.

Because nach takes the dative case when it means after.

• der Auszug = the move-out / departure
• masculine noun, so in the dative it becomes dem Auszug

So:

• nach dem Auszug = after the move-out

A native English speaker often expects something more like an accusative object after after, but German uses a preposition here, and that preposition requires dative.

Here, Auszug means moving out, departure, or the move-out.

It comes from the verb ausziehen, which can mean to move out.

Be careful: Auszug can also mean an excerpt in other contexts, but here the context clearly shows it means moving out of a place.

This is a common German structure: bleiben + another verb in the infinitive to describe a state that continues.

Here:

• bleiben = remain / stay
• stehen = stand

So stehen bleiben here means something like:

• remain standing
• be left standing

With objects like boxes or furniture, German often uses stehen, liegen, or hängen depending on position:

• stehen = stand upright
• liegen = lie / be lying
• hängen = hang

So the sentence suggests the moving boxes are still there in an upright position.

Because bleiben is the finite verb and takes the normal second position in a main clause, while stehen is an infinitive that goes to the end.

German often creates this kind of verb bracket:

• Nach dem Auszug | bleiben | ... | stehen

This is very normal with structures like:

• Er bleibt sitzen.
• Die Tür bleibt offen stehen.
• Die Kisten bleiben im Flur stehen.

So the last verb is not random; it belongs there.

Nur noch is a very common phrase meaning something like:

• only ... left
• only ... still
• nothing but ... now

In this sentence:

• nur noch zwei Umzugskartons = only two moving boxes left

The word noch adds the idea that this is what remains at this point, after other things are already gone.

Compare:

• nur zwei Umzugskartons = only two moving boxes
• nur noch zwei Umzugskartons = only two moving boxes left now

Because this sentence describes location, not movement toward a destination.

• im Flur = in the hallway / in the corridor
• in den Flur = into the hallway

German uses:

• dative for location: wo? = where?
• accusative for direction: wohin? = where to?

Here the boxes are already there, so it is location:

• im Flur = in dem Flur (contracted form)

No. Flur usually means:

• hallway
• corridor
• entry hall

It does not mean floor in the English sense of a storey of a building.

That is a common false-friend problem for English speakers.

Because German often uses a number + noun without an article.

So:

• zwei Umzugskartons = two moving boxes

That is completely normal. English does the same:

• two boxes, not the two boxes, unless you want to make them specific.

Also, this noun phrase is the subject of the sentence, even though it comes after the verb.

Because it is the thing that remains.

In German, the subject does not always have to come before the verb. Since Nach dem Auszug is placed first, the finite verb bleiben must come second, and the subject comes after it.

Structure:

• Nach dem Auszug = first element
• bleiben = finite verb in second position
• nur noch zwei Umzugskartons = subject
• im Flur = location
• stehen = infinitive at the end

So even though the subject is not first, it is still the subject.

German main clauses follow the V2 rule: the finite verb must be in second position.

If you choose to begin with a time phrase like Nach dem Auszug, then the verb comes next:

• Nach dem Auszug bleiben ...

That pushes the subject behind the verb.

You could also say:

• Nur noch zwei Umzugskartons bleiben nach dem Auszug im Flur stehen.

That version puts the subject first, but the original sentence sounds very natural because it emphasizes after the move-out.

Yes, but the meaning would change slightly.

• Nach dem Auszug stehen nur noch zwei Umzugskartons im Flur.
  = After the move-out, only two moving boxes are in the hallway.

• Nach dem Auszug bleiben nur noch zwei Umzugskartons im Flur stehen.
  = After the move-out, only two moving boxes remain standing in the hallway.

The version with bleiben emphasizes that these boxes are left behind / still there.

Because German loves compound nouns.

• Umzug = move / relocation
• Karton = cardboard box / carton

Together:

• Umzugskarton = moving box
• plural: Umzugskartons

English often uses separate words, while German often combines them into one noun.

Because Karton usually forms its plural as Kartons.

So:

• singular: der Umzugskarton
• plural: die Umzugskartons

Many German nouns borrowed from French or other languages use -s in the plural, and Karton is one of them.

Yes. German often uses positional verbs more specifically than English does.

For objects, German distinguishes how they are situated:

• stehen for things upright, like bottles, boxes, furniture
• liegen for things lying flat
• hängen for things hanging

So if the boxes are upright in the hallway, stehen is exactly what German would normally say.