W domu brakuje kawy.

Because w meaning in normally requires the locative case when it refers to location.

The noun dom has the locative singular form domu, so:

• dom = house/home
• w domu = in the house / at home

For this word, domie is not the standard form in modern Polish. The usual form is domu.

So the pattern here is:

• w + locative
• w domu = in the house / at home

Brakuje is the 3rd person singular present tense of the verb brakować.

• brakować = to be lacking / to be missing / to run short of
• brakuje = is lacking / there is a shortage of

In this sentence, Polish uses an impersonal construction. There is no normal subject like coffee in the nominative. Instead, the sentence is built around the idea that coffee is lacking.

So W domu brakuje kawy is structured more like:

• In the house, there is a lack of coffee
• or more naturally in English: There’s no coffee at home / We’re out of coffee at home

Because brakować usually takes the thing that is missing in the genitive case, not the nominative.

• kawa = coffee
• kawy = of coffee (genitive singular)

So:

• brakuje kawy = there is a lack of coffee

This is one of the most important things to remember with brakować: the missing item is usually in the genitive.

Compare:

• Kawa jest na stole. = The coffee is on the table.
  Here kawa is nominative because it is the subject.

• Brakuje kawy. = Coffee is lacking / There is no coffee.
  Here kawy is genitive because of brakuje.

Not exactly. In this sentence, Polish does not say we are missing coffee in a normal personal way. Instead, it uses an impersonal structure:

• brakuje kawy = coffee is lacking

So there is no explicit grammatical subject like we.

However, in real-life meaning, English often translates it as:

• We’re out of coffee
• There’s no coffee at home

The people affected are understood from context, but they are not directly stated in the grammar of this sentence.

It can mean either, depending on context.

With dom, Polish often overlaps the ideas of:

• house
• home

So w domu can mean:

• in the house
• at home

In W domu brakuje kawy, English would often use at home if you are talking about your household in general:

• There’s no coffee at home.

But in the house is also possible if you want to stress the physical location.

Yes, absolutely. That is a very natural sentence.

• Nie ma kawy w domu. = There is no coffee at home.
• W domu brakuje kawy. = There is a lack of coffee at home / We’re out of coffee at home.

The difference is mainly one of nuance:

• nie ma simply states absence
• brakuje suggests lack or shortage, often with the idea that the thing is wanted or needed

So if you just want to say the coffee is not there, nie ma kawy is very common. If you want to emphasize that the household is short of coffee, brakuje kawy works well.

No. It can also be used with people, feelings, qualities, time, money, and so on.

For example:

• Brakuje czasu. = There isn’t enough time.
• Brakuje pieniędzy. = There’s not enough money.
• Brakuje cukru. = There’s no sugar / We’re short of sugar.

It can also be used with a person in the dative:

• Brakuje mi kawy. = I’m missing coffee / I need coffee.
• Brakuje mi ciebie. = I miss you.

So brakować is a very useful verb, but the grammar changes depending on what is being expressed.

Because Polish often expresses that idea without a direct equivalent of English there is.

In English, we often say:

• There is no coffee at home.

In Polish, one common way is:

• W domu brakuje kawy.

Polish does not need a dummy subject like there. The sentence is built directly around the verb brakuje and the location w domu.

So this is a normal difference between English and Polish sentence structure.

Yes. Polish word order is more flexible than English word order.

You could also hear:

• Brakuje kawy w domu.
• Kawy brakuje w domu.

But W domu brakuje kawy is very natural because it starts with the location and then gives the new information: coffee is lacking there.

Very roughly:

• W domu brakuje kawy.
  Focuses first on at home

• Brakuje kawy w domu.
  Slightly more neutral or conversational

• Kawy brakuje w domu.
  Can emphasize coffee as the thing lacking

So the original sentence is perfectly normal, but not the only possible order.

It is singular genitive.

• kawa = coffee
• kawy = of coffee

Even though English mass nouns like coffee do not always feel singular in the same way, Polish treats kawa as a singular noun here.

If you were talking about multiple kinds or portions in a different context, other forms might appear, but in this sentence kawy is simply the genitive singular form of kawa.