Wij leggen de arbeidsplaats en de ingangsdatum vast.

Because vastleggen is a separable verb in Dutch.

• The full infinitive is vastleggen = to determine, to fix, to lay down formally
• In a main clause, Dutch usually splits separable verbs:
  • Wij leggen ... vast.
• In the infinitive or in some other structures, the parts stay together:
  • Wij willen de arbeidsplaats vastleggen.
  • Omdat wij de arbeidsplaats vastleggen.

So leggen ... vast is not just lay ... fixed word-for-word; it is the normal split form of the verb vastleggen.

No. Leggen and vastleggen are different verbs.

• leggen usually means to lay, to put, or to place
• vastleggen means to fix, to establish, to determine, or to record formally

So in this sentence, you should understand the verb as vastleggen, not just leggen.

Examples:

• Ik leg het boek op tafel. = I put the book on the table.
• Wij leggen de datum vast. = We set/fix the date.

Arbeidsplaats literally means something like place of work or workplace.

In this kind of formal or HR-related sentence, it usually refers to:

• the employee’s workplace
• the work location
• sometimes the official place where the employee will work

A more everyday Dutch word is often werkplek, but arbeidsplaats sounds more formal and administrative.

Ingangsdatum is a formal word meaning the start date or effective date.

It is often used for:

• contracts
• employment
• legal documents
• policies or agreements

So in this sentence, it most likely means the date on which the job or agreement officially begins.

Because both nouns are de-words in Dutch, and each noun phrase normally takes its own article.

So:

• de arbeidsplaats
• de ingangsdatum

Dutch often repeats the article when linking two separate nouns with en:

• de man en de vrouw
• het contract en de voorwaarden
• de arbeidsplaats en de ingangsdatum

This is very natural and standard.

Usually, the full version with both articles is better and more natural here:

• Wij leggen de arbeidsplaats en de ingangsdatum vast.

Leaving out the second article is sometimes possible in certain coordinated expressions, but in a formal sentence like this, repeating de sounds clearer and more standard.

So for learners, it is best to keep:

• de arbeidsplaats en de ingangsdatum

Because wij means we, and the verb must agree with the subject.

The present tense of leggen is:

• ik leg
• jij legt
• u legt
• hij/zij/het legt
• wij leggen
• jullie leggen
• zij leggen

So with wij, the correct form is leggen.

Here it simply means we.

In Dutch, wij and we both mean we:

• wij is the fuller, more stressed form
• we is the unstressed, very common everyday form

So this sentence could also be:

• We leggen de arbeidsplaats en de ingangsdatum vast.

Both are correct. Wij may sound slightly more formal or emphatic.

This is a normal main clause in Dutch.

The basic pattern is:

• Subject: Wij
• Finite verb: leggen
• Object(s): de arbeidsplaats en de ingangsdatum
• Separable prefix: vast

So the structure is:

• Wij | leggen | de arbeidsplaats en de ingangsdatum | vast

This is typical Dutch word order with separable verbs in a main clause.

In a subordinate clause, the separable verb usually becomes one whole verb again and moves toward the end.

Main clause:

• Wij leggen de arbeidsplaats en de ingangsdatum vast.

Subordinate clause:

• ..., omdat wij de arbeidsplaats en de ingangsdatum vastleggen.

So:

• main clause: leggen ... vast
• subordinate clause: vastleggen

This is an important pattern in Dutch.

It is often a bit more formal than everyday English set or decide, but it is very common and useful.

Depending on context, vastleggen can mean:

• to determine
• to set
• to establish
• to record
• to formalize

Examples:

• We leggen de afspraak vast. = We record/formalize the agreement.
• Ze leggen de datum vast. = They set the date.
• De regels zijn vastgelegd. = The rules have been laid down / established.

In your sentence, it has a formal, administrative tone.

In Dutch yes/no questions, the verb usually comes first.

Statement:

• Wij leggen de arbeidsplaats en de ingangsdatum vast.

Question:

• Leggen wij de arbeidsplaats en de ingangsdatum vast?

This means:

• Are we determining the workplace and the start date?
• or Do we determine the workplace and the start date?

The separable part vast still stays at the end in the main clause question.

It sounds mostly formal and administrative, especially because of:

• arbeidsplaats
• ingangsdatum
• vastleggen

You are likely to see this in:

• contracts
• HR documents
• onboarding materials
• official emails

In more everyday Dutch, people might use simpler wording such as:

• We spreken de werkplek en de startdatum af.
• We bepalen de werkplek en de startdatum.

But the original sentence is perfectly correct and natural in a formal context.