Zaterdag werken wij niet.

Dutch often puts a time expression first if that is the topic of the sentence. Starting with Zaterdag is very natural and means something like As for Saturday... or On Saturday...

So Zaterdag werken wij niet is a normal way to say that Saturday is the important time frame.

In a main clause, Dutch usually follows the verb-second rule. That means the finite verb must be in the second position.

Here, Zaterdag takes the first position, so the verb werken must come next:

• Zaterdag = position 1
• werken = position 2
• wij = comes after the verb

That is why you get:

• Zaterdag werken wij niet.

If the subject comes first, then the order changes:

• Wij werken zaterdag niet.

Both are correct.

Dutch often uses days of the week without a preposition when they function as time expressions.

So Dutch can simply say:

• Zaterdag werken wij niet.

Literally this looks like Saturday we do not work, but it means On Saturday we do not work.

You can also say:

• Op zaterdag werken wij niet.

That is also correct, and can sound a bit more explicit. In many cases, both versions are possible.

In Dutch, niet often comes late in the sentence, especially when it negates the main idea of the clause.

In Zaterdag werken wij niet, niet negates werken:

• werken = to work
• niet werken = not work

Putting niet at the end is very natural here.

Yes. That is also correct.

Compare:

• Zaterdag werken wij niet.
• Wij werken zaterdag niet.

The meaning is basically the same, but the focus is slightly different:

• Zaterdag werken wij niet puts Saturday first for emphasis or topic.
• Wij werken zaterdag niet starts more neutrally with we.

Both wij and we mean we.

• wij is the full/stressed form
• we is the unstressed/common spoken form

So you could also say:

• Zaterdag werken we niet.

That is very common in everyday Dutch.

Using wij can sound a bit more formal, emphatic, or careful.

It can mean either, depending on context.

It may mean:

• We are not working this Saturday
• We do not work on Saturdays

Dutch often leaves this to context.

If you want to make the habitual meaning clearer, people often say:

• Op zaterdag werken wij niet.

If you want to make this coming Saturday clearer, context usually does the job, or you might say:

• Aanstaande zaterdag werken wij niet.

In Dutch, days of the week are normally not capitalized.

So normally it is:

• zaterdag

But here it is the first word of the sentence, so it gets a capital letter:

• Zaterdag werken wij niet.

That is the same reason English capitalizes the first word of a sentence, although unlike English, Dutch does not capitalize day names in the middle of a sentence.

No. Normally there is no comma here.

A sentence like:

• Zaterdag werken wij niet.

does not need punctuation after the time expression. The word Zaterdag is just the first element of the sentence, not a separate phrase that needs to be set off with commas.

No. Here werken is the present tense plural form of the verb werken.

For wij/we, the present tense is:

• ik werk
• jij werkt
• hij/zij werkt
• wij werken
• jullie werken
• zij werken

So in this sentence, werken means work / are working, not to work.

Not in normal Dutch. That sounds wrong or extremely unnatural.

Dutch word order in a main clause normally keeps the finite verb in second position, and niet does not usually go first like that.

Natural options are:

• Zaterdag werken wij niet.
• Wij werken zaterdag niet.

Those are the forms you should learn first.