Der skal være et stempel på dokumentet, ellers gælder det ikke.

Here der is a dummy subject, much like there in English expressions such as There must be...

So:

• Der skal være et stempel... = There must be a stamp...

It does not mean there as a location. It is just used to introduce the existence or presence of something.

This pattern is very common in Danish:

• Der er en bil udenfor. = There is a car outside.
• Der skal være ro. = There must be quiet.

Skal is a modal verb. In this sentence it expresses requirement or necessity.

So:

• skal være = must be / has to be

That means the sentence is not just describing a fact. It is stating a rule or requirement.

Compare:

• Der er et stempel på dokumentet. = There is a stamp on the document.
• Der skal være et stempel på dokumentet. = There must be a stamp on the document.

Because stempel is a neuter noun in Danish.

Danish nouns have two grammatical genders:

• common gender → usually takes en
• neuter gender → takes et

So:

• et stempel = a stamp

You simply have to learn the gender with the noun.

Useful forms:

• et stempel = a stamp
• stemplet = the stamp
• stempler = stamps
• stemplerne = the stamps

There are two things going on here:

1. på means on
2. dokumentet is the definite form, meaning the document

So:

• på dokumentet = on the document

The noun dokument is neuter:

• et dokument = a document
• dokumentet = the document

Using på makes sense because a stamp is placed on a document.

In Danish, the definite article is usually added to the end of the noun.

So:

• et dokument = a document
• dokumentet = the document

This is very different from English, where the is a separate word.

You only use a separate determiner like det before the noun in certain structures, for example with adjectives:

• dokumentet = the document
• det officielle dokument = the official document

Ellers here means otherwise.

So the second part of the sentence means:

• otherwise, it is not valid
• if not, it does not count / is not valid

It connects the requirement in the first clause with the consequence in the second clause.

Example idea:

• Du skal skrive under, ellers gælder det ikke. = You must sign it, otherwise it is not valid.

Because Danish is a V2 language in main clauses. That means the finite verb normally comes in the second position.

Here, ellers is placed first, so the verb must come next:

• Ellers gælder det ikke.

Structure:

• Ellers = first position
• gælder = second position
• det = subject after the verb

This is very typical Danish word order.

Compare:

• Det gælder ikke. = It is not valid.
• Ellers gælder det ikke. = Otherwise it is not valid.

English does not usually do this, so it often feels strange to learners.

Gælde can mean several related things, including:

• to be valid
• to apply
• to count

In this sentence, gælder det ikke means something like:

• it is not valid
• it does not count
• it does not apply

Because the context is a document, is not valid is usually the best translation.

Forms of the verb:

• at gælde = to be valid / apply
• gælder = is valid / applies
• gjaldt = was valid / applied
• har gældt = has been valid / has applied

Det refers to the thing being discussed — most naturally the document or the document as a valid official item.

So the idea is:

• if there is no stamp on the document, it is not valid

Danish often uses det in a general way like this, especially when the context already makes the reference clear.

The comma separates two clauses:

• Der skal være et stempel på dokumentet
• ellers gælder det ikke

So the comma helps show that the second clause gives the consequence of the first.

In modern Danish, comma rules can vary a little depending on the comma system being used, but this comma is completely natural and expected here.

It can mean either, depending on context.

Stempel can refer to:

• a physical stamp
• a seal
• an official marking proving something is approved or authentic

In a sentence about a document, it often suggests an official stamp/seal rather than a postage stamp.

So if the meaning shown to the learner is something like There must be an official stamp on the document, otherwise it is not valid, that fits very well.

The main stress would usually fall on the important content words:

• Der skal være et stempel på dokumentet, ellers gælder det ikke.

That helps highlight:

• the required item: stempel
• the consequence: gælder det ikke

Function words like der, et, på, and det are usually less stressed.

A fairly literal version would be:

• There shall be a stamp on the document, otherwise it applies not.

That is not natural English, but it helps show the Danish structure.

A natural English translation would be:

• There must be a stamp on the document, otherwise it isn’t valid.