Wij controleren de achtknoop en de zekerlus.

Yes. Wij and we both mean we.

• Wij is the fuller, slightly more emphatic form.
• We is very common in everyday speech and writing.

So this sentence could also be:

We controleren de achtknoop en de zekerlus.

That sounds completely natural.

Because with wij in the present tense, Dutch regular verbs usually take the full plural form, which is the same as the infinitive.

For controleren:

• ik controleer
• jij controleert
• hij/zij controleert
• wij controleren

So wij controleren is the correct present-tense form.

Mostly yes. In this sentence, the order is:

• Wij = subject
• controleren = verb
• de achtknoop en de zekerlus = object

So it follows the basic pattern:

subject + verb + object

That is very similar to English.

A useful Dutch rule is that in a main clause, the finite verb normally comes in second position. Here, the subject is first, so the verb comes right after it.

Because both nouns take the article de, so Dutch can use one article for both:

de achtknoop en de zekerlus

This works the same way as in English:

the knot and the loop

You could repeat the article, but you usually do not need to:

de achtknoop en de zekerlus
or
de achtknoop en de zekerlus

In this case, one de is the normal, natural choice.

Because these nouns are de-words. In Dutch, singular nouns take either:

• de
• het

Unfortunately, this is something you often have to learn with each noun.

A good habit is to memorize nouns together with their article:

• de achtknoop
• de zekerlus

That is much better than learning just the bare noun by itself.

Because Dutch very often forms compound nouns by writing the parts together as a single word.

So instead of writing separate words, Dutch combines them:

• acht + knoop → achtknoop
• zeker + lus → zekerlus

This is very common in Dutch, especially with technical or practical vocabulary.

English often uses separate words where Dutch prefers one compound word.

En means and.

It links the two nouns:

• de achtknoop
• de zekerlus

So the sentence says that both items are being checked.

Yes. It is the present tense.

It can mean:

• we check
• we are checking

Just like in Dutch generally, the simple present can often cover both a habitual meaning and a current action, depending on context.

Yes, a few.

• wij: the ij sound can be tricky. It does not sound exactly like English ay or eye, though English speakers often start with something close to why.
• achtknoop: the ch in acht is the guttural Dutch sound, not the English ch in church.
• controleren: this word is fairly familiar-looking, but the Dutch pronunciation is still different from English control.
• zekerlus: the z is voiced, like English z, and u in lus is not the same as English oo.

If you want, I can also break the whole sentence down word by word with pronunciation help.

It is basically neutral.

Nothing in it is especially formal or informal. The only small point is:

• wij sounds a bit fuller or slightly more careful than we
• we is often more conversational

But the sentence itself is normal Dutch in either case.

Yes. The grammar stays the same:

• Wij controleren de achtknoop en de zekerlus.
• We controleren de achtknoop en de zekerlus.

Both are correct. The difference is mostly style and emphasis, not grammar or meaning.