Ons toets die dreineerpomp, pompfilter, deurgrendel, rubberseël en wasmiddellaai.

Yes. Ons means we in this sentence.

So Ons toets ... = We test ...

A useful extra point: in Afrikaans, ons can also mean us in other contexts, depending on sentence structure. Here, because it comes before the verb, it is clearly the subject we.

Afrikaans verbs usually do not change form for different subjects the way English verbs sometimes do.

So you get:

• Ek toets = I test
• Jy toets = you test
• Ons toets = we test
• Hulle toets = they test

That makes Afrikaans verb conjugation much simpler than English.

Because die applies to the entire list of items that follow.

So:

• die dreineerpomp, pompfilter, deurgrendel, rubberseël en wasmiddellaai

means the drain pump, pump filter, door latch, rubber seal and detergent drawer.

This works much like English, where you can also say the drain pump, pump filter, door latch, rubber seal and detergent drawer without repeating the before every noun.

You could repeat die before each item, but it is usually unnecessary unless you want extra emphasis or clarity.

Yes. Afrikaans uses die as the definite article for both singular and plural nouns.

Examples:

• die pomp = the pump
• die pompe = the pumps

Unlike some other languages, Afrikaans does not change the for gender or case.

Because Afrikaans very often writes compound nouns as one word.

This is very common and very important in Afrikaans spelling.

For example:

• dreineerpomp = drain + pump
• pompfilter = pump + filter
• deurgrendel = door + latch/lock
• rubberseël = rubber + seal
• wasmiddellaai = washing-agent + drawer, meaning detergent drawer

English often writes similar expressions as two words, hyphenated words, or one word depending on the term. Afrikaans strongly prefers a single compound noun.

Yes:

• dreineer = to drain
• pomp = pump

So dreineerpomp literally means draining pump or drain pump.

This kind of construction is very normal in Afrikaans technical vocabulary.

It is a compound noun:

• deur = door
• grendel = latch, bolt, or locking mechanism

So deurgrendel is the door latch or door lock mechanism.

The exact English translation can vary a little depending on the machine or technical context, but the basic idea is the part that secures the door.

The two dots in seël are a diaeresis. They show that the vowels are pronounced separately.

So seël is not treated as one blended vowel sound. It is pronounced more like see-əl than a single smooth vowel.

This spelling helps the reader see the syllable division more clearly.

It is another compound noun:

• wasmiddel = detergent
• laai = drawer

And wasmiddel itself can be broken down further:

• was = wash
• middel = means/agent/substance

So wasmiddellaai literally means detergent drawer.

Yes, very similar.

The structure is:

• Ons = subject
• toets = verb
• die dreineerpomp, pompfilter, deurgrendel, rubberseël en wasmiddellaai = object/list of things being tested

So the sentence follows a straightforward subject–verb–object pattern, just like English:

• We test the drain pump, pump filter, door latch, rubber seal and detergent drawer.

Because in Afrikaans, as in normal English style, you usually do not need a comma before en when it simply joins the last item in a list.

So:

• A, B, C en D

is the normal pattern.

A comma before en is only used in special cases, such as when it helps avoid confusion.

Afrikaans does not have grammatical gender in the way languages like German or Dutch do.

So nouns like dreineerpomp, pompfilter, deurgrendel, rubberseël, and wasmiddellaai do not take different articles based on masculine, feminine, or neuter gender.

That is one reason why die is so useful: it works broadly without gender changes.

A rough English-friendly guide would be:

Ons toets die dreineerpomp, pompfilter, deurgrendel, rubberseël en wasmiddellaai.

Approximate pronunciation:

ons toost dee DRAY-neer-pomp, pomp-fil-ter, duhr-GREN-del, RUY-ber-seel, en VUS-mid-del-lie

A few notes:

• oo in toets is not exactly English oo, but the rough guide helps.
• g in grendel is the usual Afrikaans guttural sound, which English does not really have.
• w in wasmiddel sounds more like English v.
• seël has two syllable parts because of the diaeresis.

If you want, I can also give you a more careful syllable-by-syllable pronunciation guide.