Koště je za dveřmi.

Koště is in the nominative singular because it is the subject of the sentence.

Its gender is neuter. A good way to remember that is that you would say to koště for the broom / this broom.

So grammatically:

• koště = nominative singular
• gender = neuter

Je is the 3rd person singular present tense of být (to be), so it means is.

It agrees with koště, which is singular:

• koště je = the broom is

Czech often leaves out subject pronouns like he, she, or it, but it normally keeps the verb. So you say:

• Koště je za dveřmi.

not usually just

• Koště za dveřmi.

unless you are speaking very informally, making a note, or using a headline-like style.

Because za changes case depending on meaning.

With location (where something is), za takes the instrumental:

• za dveřmi = behind the door / behind the doors

With movement toward a position (where something is going), za takes the accusative:

• Dám koště za dveře. = I’ll put the broom behind the door.

So:

• Koště je za dveřmi. = location, so instrumental
• Dám koště za dveře. = motion, so accusative

Because dveře is a plural-only noun in Czech. This is very common for learners to notice.

Even when English uses singular door, Czech usually uses dveře, which is grammatically plural. That is why the instrumental form is dveřmi.

So the pattern is:

• nominative: dveře
• instrumental: dveřmi

This is normal Czech usage, not a special exception just for this sentence.

The dictionary form is dveře.

In this sentence, it appears as dveřmi, which is the instrumental plural form.

So:

• dictionary form: dveře
• form used here: dveřmi

This is one of those nouns you simply have to get used to seeing in plural forms.

Not always. Za has several meanings depending on context and case.

In this sentence, za dveřmi means behind the door or on the other side of the door, depending on the situation.

Some other uses of za are different, for example:

• za domem = behind the house
• za hodinu = in an hour
• děkuji za pomoc = thank you for the help

So here it is specifically a location preposition meaning behind.

Yes. Czech word order is flexible, but the emphasis changes.

The sentence:

• Koště je za dveřmi.

is a natural neutral way to say it.

You could also say:

• Za dveřmi je koště.

This version puts more attention on where the broom is, or it can sound like you are introducing what is there behind the door.

So both are grammatical, but they do not sound exactly the same in terms of emphasis.

Because Czech has no articles. There is no direct equivalent of English a/an or the in ordinary sentences.

So:

• koště can mean a broom or the broom
• dveřmi can mean door(s) depending on context

English needs articles, but Czech usually does not. The exact meaning is understood from context.

You know it from the noun itself and from the verb.

• koště is singular
• je is also singular

Czech does not need a separate pronoun like it in this kind of sentence. The verb form already tells you the number, and the noun tells you what the subject is.

So Koště je... already clearly means The broom is... / A broom is...

A rough learner-friendly pronunciation would be:

KOSH-tyeh yeh za DVYE-rzh-mee

A few important sound notes:

• š sounds like sh in shoe
• ť is a soft t sound
• j in je sounds like English y
• ř is the famous Czech sound that has no exact English equivalent; learners often start with something between r and zh

You do not need perfect pronunciation right away. The hardest part here is usually dveřmi.

For a beginner, the most useful thing is to remember that koště is neuter and that its nominative singular form is koště.

Its full declension is not one of the very simplest patterns, so some of its other forms may look less predictable later. But in this sentence, you only need to recognize that:

• koště is the subject
• it is nominative singular
• it is neuter

So for now, treat it as a vocabulary item with gender:

• to koště

Yes, depending on context.

Za dveřmi can mean:

• behind the door in a physical sense, for example leaning against the wall behind an open door
• on the other side of the door, depending on how the speaker imagines the space

In many everyday situations, Czech speakers use za dveřmi naturally without carefully separating those two ideas. The context usually makes it clear.