De naam van de afzender staat op de achterkant van de envelop.

In Dutch, staan is very often used when text or information is written, printed, or displayed somewhere.

So De naam van de afzender staat op de achterkant van de envelop means that the sender’s name is physically written/printed there.

Compare:

• De naam is op de envelop = understandable, but less natural
• De naam staat op de envelop = the normal Dutch way to say it

Dutch also uses staan for things like:

• Het staat op het bord.
• Mijn adres staat op de brief.
• Wat staat er op het etiket?

So here, staat is about location of written information, not about standing upright in the literal sense.

Here van means of.

It links two nouns together:

• de naam van de afzender = the name of the sender
• de achterkant van de envelop = the back side of the envelope

Dutch uses van very often where English might use either of or ’s.

For example:

• de naam van de afzender
  English could be the sender’s name or the name of the sender
• de kleur van de auto
  = the car’s color / the color of the car

So this is a very common Dutch structure.

Because Dutch loves compound nouns.

When two nouns combine into one idea, Dutch normally writes them as a single word:

• achter
  • kant → achterkant
• envelop
  • papier → enveloppapier
• tafel
  • blad → tafelblad

English often writes these as two words, but Dutch usually does not.

A useful rule: in a Dutch compound noun, the last part is the main noun.
So in achterkant, the main noun is kant. That is why:

• the article is de: de achterkant
• the plural is based on kant: de achterkant / de achterkanten

Because Dutch main clauses usually follow the verb-second rule.

That means the finite verb comes in the second position:

• De naam van de afzender = first position
• staat = second position

Even though De naam van de afzender contains several words, it counts as one whole chunk.

So the structure is:

• De naam van de afzender | staat | op de achterkant van de envelop

This is one of the most important word-order rules in Dutch.

Yes, absolutely.

That sentence is perfectly correct:

Op de achterkant van de envelop staat de naam van de afzender.

The meaning stays basically the same, but the focus shifts a little:

• De naam van de afzender staat ... puts the emphasis first on the sender’s name
• Op de achterkant van de envelop staat ... puts the emphasis first on the location

And the verb still stays in second position:

• Op de achterkant van de envelop = first position
• staat = second position

So this is a good example of how Dutch word order can change for emphasis while keeping the verb-second rule.

Op is used because the name is written on the surface of something.

So:

• op de achterkant = on the back
• literally, on the back side/surface

This is the natural preposition for writing or printing on paper, labels, signs, envelopes, and so on.

For example:

• Het adres staat op de brief.
• Er staat een stempel op de envelop.
• Schrijf je naam op het papier.

Using aan here would sound wrong, and achter means behind, not on the back side.

So:

• op de achterkant = on the back side
• achter de envelop = behind the envelope

Those are very different.

Because all four nouns in this sentence are de-words:

• de naam
• de afzender
• de achterkant
• de envelop

Unfortunately, whether a noun takes de or het often has to be learned word by word, but there are some helpful patterns:

• words for people are usually de → de afzender
• compounds take the gender of the last part → de achterkant because de kant
• naam and envelop are simply nouns you memorize as de-words

So there is no special rule in this sentence causing all of them to be de; it just happens that each noun individually is a de-word.

In a normal full sentence, Dutch usually needs the article here:

• de naam van de afzender

That refers to a specific sender in the situation.

Without the article, van afzender, it sounds incomplete in ordinary sentence style. However, you may sometimes see article-less noun phrases in very short labels, forms, or headings, such as:

• naam afzender
• adres afzender

That is more like note-taking or form language, not normal full-sentence Dutch.

So in a complete sentence, de afzender is the natural choice.

They are very similar.

• de achterkant = the back, the back side
• de achterzijde = the back side, often a bit more formal or technical

In everyday Dutch, achterkant is very common and natural.
Achterzijde may sound slightly more formal, careful, or written.

So both of these are possible:

• op de achterkant van de envelop
• op de achterzijde van de envelop

But achterkant feels more everyday in most situations.

Because Dutch does not capitalize ordinary nouns the way German does.

So in Dutch:

• de naam
• de afzender
• de achterkant
• de envelop

Only the first word of the sentence and proper names normally get a capital letter.

That is why you write:

• De naam van de afzender staat op de achterkant van de envelop.

and not capitalized versions like English learners sometimes expect after seeing German.