De afspraak is om vijftien uur.

Yes. Afspraak can mean a few related things in Dutch, depending on context:

• appointment: a planned meeting at a certain time
• date: sometimes a romantic meeting
• agreement/arrangement: something people have agreed on

In De afspraak is om vijftien uur, the most natural meaning is appointment or planned meeting.

Because afspraak is a de-word in Dutch. Dutch nouns take either de or het, and this usually has to be learned with the noun.

So:

• de afspraak = correct
• het afspraak = incorrect

For an English speaker, it often helps to memorize nouns together with their article:

• de afspraak
• het huis
• de tafel

Here, om is the preposition used before a clock time. In English, it corresponds to at.

So:

• om vijftien uur = at 15:00
• om drie uur = at three o’clock

This is very common in Dutch:

• De les begint om negen uur.
• Ik kom om half acht.

Dutch often uses the 24-hour clock, especially in formal, written, official, or practical contexts.

So:

• vijftien uur = 15:00
• in 12-hour time, that is three o’clock in the afternoon

This is completely normal in Dutch. You will often see and hear times like:

• veertien uur = 14:00
• achttien uur = 18:00

Yes, absolutely.

• De afspraak is om vijftien uur.
• De afspraak is om drie uur.

Both can be correct, depending on the situation.

However, drie uur by itself can sometimes be ambiguous, because it could mean 3 a.m. or 3 p.m. if the context is not clear. If you want to make it clear that it is in the afternoon, you can say:

• om drie uur 's middags

So:

• om vijftien uur = unambiguously 15:00
• om drie uur 's middags = also unambiguously 15:00

Yes, but it depends on the context.

Dutch speakers often use the 24-hour system in:

• schedules
• travel information
• work settings
• formal situations
• phone calls about appointments

In casual speech, many people would also say:

• om drie uur
• om drie uur 's middags

So om vijftien uur is perfectly natural, but it may sound a bit more precise or formal than om drie uur.

This is a basic Dutch sentence pattern:

• De afspraak = subject
• is = verb
• om vijftien uur = time expression / complement

So the structure is:

subject + verb + time

This is very normal in Dutch main clauses:

• De vergadering is om tien uur.
• Het feest begint om acht uur.

Nothing unusual is happening here.

Yes, you can. That puts more emphasis on the time.

Compare:

• De afspraak is om vijftien uur.
  Neutral, straightforward.

• Om vijftien uur is de afspraak.
  More emphasis on when it is.

In the second sentence, Dutch uses normal inversion after a fronted element:

• Om vijftien uur
  • is
    • de afspraak

That is a very common Dutch pattern.

Because Dutch simply uses om before the time phrase. That is the normal way to express at with specific clock times.

So Dutch does not need anything extra here:

• is om vijftien uur
• literally: is at fifteen o’clock

This is just the standard Dutch construction.

Yes. De makes it definite, so it refers to a specific appointment that both speaker and listener can identify.

• de afspraak = the appointment
• een afspraak = an appointment

So:

• De afspraak is om vijftien uur.
  A specific appointment is being discussed.

If you said:

• Een afspraak is om vijftien uur.

that would usually sound less natural unless you were introducing one appointment among others.

A rough pronunciation guide for an English speaker:

• afspraak ≈ AHF-spraakh
• vijftien ≈ something like vife-TEEN, but with a Dutch ij sound that is not exactly English ai
• uur ≈ a rounded vowel sound that English does not really have, followed by a soft r

A few notes:

• aa in afspraak is a long vowel.
• ij in vijftien is one of the trickier Dutch sounds for English speakers.
• uu in uur is also difficult at first; it is not the same as English oo.

If you are learning pronunciation, uur is especially worth practicing separately.

Yes, om can have other meanings in other contexts, including meanings related to movement or position, and English learners may associate it with around in some phrases.

But before a clock time, om specifically means at.

So in this sentence:

• om vijftien uur = at 15:00

There is no idea of approximation here. It is a specific time.

If Dutch wanted to say around 15:00, it would use something else, for example:

• rond vijftien uur
• ongeveer om vijftien uur