Die modelnommer en aankoopdatum is op die waarborgbewys.

Because in the present tense, Afrikaans uses is for all persons and numbers:

• ek is
• jy is
• hy/sy is
• ons is
• julle is
• hulle is

So unlike English, Afrikaans does not change from is to are. The plural idea is shown by the nouns, not by a different verb form.

Die is the definite article, so it means the.

It is pronounced roughly like dee, not like the English verb die.

A useful thing to remember: Afrikaans uses die for both singular and plural nouns, so the same word can mean:

• the model number
• the model numbers
• the warranty certificate
• the warranty certificates

Context tells you which is meant.

Afrikaans often lets one article cover two nouns joined by en (and), just as English often does:

• die modelnommer en aankoopdatum

This is like saying the model number and purchase date.

You can also say:

• die modelnommer en die aankoopdatum

That is also correct. Repeating die can sound a little more explicit, but it is not necessary.

Because Afrikaans commonly forms compound nouns as a single written word.

So:

• model + nommer → modelnommer
• aankoop + datum → aankoopdatum
• waarborg + bewys → waarborgbewys

This is very normal in Afrikaans. English often writes similar ideas as two words, but Afrikaans usually joins them.

A helpful rule: the last part is usually the main noun, and the part before it describes it.

Op usually means on.

In this sentence, op die waarborgbewys means on the warranty certificate/slip, in the sense of written on it, shown on it, or appearing on it.

So it does not have to mean physically lying on top of something. With documents, labels, forms, and screens, op is often used this way.

Yes. This is standard Afrikaans main-clause word order:

• Die modelnommer en aankoopdatum = subject
• is = verb
• op die waarborgbewys = prepositional phrase

So the pattern is:

Subject + verb + rest

That is the normal structure for a simple statement.

Literally, it is:

• waarborg = warranty/guarantee
• bewys = proof, evidence, certificate

So waarborgbewys means something like:

• warranty certificate
• warranty slip
• proof of warranty

The exact English wording depends on context, but the idea is the document that serves as the warranty proof.

Yes, you often can.

• Die modelnommer en aankoopdatum is op die waarborgbewys.
• Die modelnommer en aankoopdatum staan op die waarborgbewys.

Both are natural, but staan op can sound a bit more specific when something is written/printed on a document.

So:

• is op = is on there
• staan op = is written/printed on there

No, not the way they are in German.

Common nouns in Afrikaans are normally written in lower-case:

• modelnommer
• aankoopdatum
• waarborgbewys

The first word Die is capitalized here only because it begins the sentence, not because it is a noun.