Pomyłka jest w numerze zamówienia.

A natural translation is There is a mistake in the order number.

Depending on context, English might also say:

• The mistake is in the order number
• There’s an error in the order number
• The order number is wrong

All of these capture the same basic idea.

Pomyłka means mistake, error, or mix-up.

It usually refers to a mistake someone made, often by accident. In many situations, it is a bit more like mistake than a formal technical error.

It is a feminine noun, which matters for agreement in other sentences.

Jest means is.

So the sentence is literally:

• Pomyłka = mistake
• jest = is
• w numerze zamówienia = in the order number

Polish often uses jest in this kind of sentence to state that something exists or is located somewhere.

You could also say:

• W numerze zamówienia jest pomyłka

This is very natural too, and it means the same thing: There is a mistake in the order number.

Because the preposition w usually takes the locative case when it means in and refers to location.

So:

• dictionary form: numer
• after w: w numerze

This is why you get numerze, not numer.

Here, w means in, so the locative is required.

Here, zamówienia is the genitive singular of zamówienie (order).

The phrase numer zamówienia means order number.

This is a very common Polish pattern:

• numer telefonu = phone number
• adres e-maila = email address
• koniec filmu = end of the film

So in numer zamówienia, the second noun tells you what kind of number it is: the number of the order.

In the full phrase:

• w numerze zamówienia

the word numerze is in the locative because of w, but zamówienia stays in the genitive because it depends on numer.

Here it is singular: of the order.

That can be confusing, because zamówienia can also be a plural form in other contexts. But in this sentence, it is understood as genitive singular of zamówienie.

So:

• zamówienie = an order
• numer zamówienia = the order’s number / order number

Yes. Polish word order is more flexible than English.

These are both natural:

• Pomyłka jest w numerze zamówienia.
• W numerze zamówienia jest pomyłka.

The meaning is basically the same, but the emphasis changes slightly:

• Pomyłka jest w numerze zamówienia puts a little more focus on the mistake
• W numerze zamówienia jest pomyłka puts a little more focus on where the mistake is

In everyday speech, the second version is often especially natural if you are answering Where is the mistake?

Because Polish does not have articles like English a and the.

So pomyłka can mean:

• a mistake
• the mistake

and numer zamówienia can mean:

• an order number
• the order number

The exact meaning depends on context.

No. W can take different cases depending on the meaning.

Most importantly:

• w + locative = in, inside, at a location

  • w domu = in the house
  • w numerze = in the number

• w + accusative can be used with motion in some expressions

  • wchodzić w coś = to go into something

In your sentence, this is a location idea, so locative is used: w numerze.

They are close, but not always identical.

• pomyłka = mistake, mix-up, slip, something done wrongly by accident
• błąd = error, mistake, fault; often a bit broader and sometimes more formal

In this sentence, both can work:

• Pomyłka jest w numerze zamówienia.
• Błąd jest w numerze zamówienia.

But pomyłka can sound a little more like someone entered it incorrectly or there was a mix-up, while błąd can sound slightly more neutral or technical.

This sentence is understandable and correct, but in real customer-service Polish, people often use slightly more natural alternatives such as:

• W numerze zamówienia jest błąd.
• Jest pomyłka w numerze zamówienia.
• Numer zamówienia jest błędny.
• W numerze zamówienia jest literówka. if it is specifically a typo

So your sentence is good Polish, but in everyday service language, a speaker might more often begin with W numerze zamówienia... or use błąd.

Numerze is pronounced approximately noo-MEH-zheh.

A few points:

• nu sounds like noo
• me sounds like meh
• rz here sounds like the zh sound in measure

So the whole phrase w numerze zamówienia sounds roughly like:

v noo-MEH-zheh za-moov-YEH-nya

That is only an approximation, but it can help you get started.