Žárovka je v pokoji.

A rough pronunciation is:

ZHAA-rof-ka ye f PO-ko-yi

A few important points:

• ž sounds like the s in measure
• á is a long a
• j sounds like English y
• v is often pronounced like f before a voiceless consonant, so:
  • žárovka sounds roughly like zhárofka
  • v pokoji sounds roughly like f pokoji
• Czech stress is usually on the first syllable of a word

So the whole sentence is pronounced approximately ZHAA-rof-ka ye f PO-ko-yi.

Word by word:

• Žárovka = light bulb
• je = is
• v = in
• pokoji = room in the form required after v

So grammatically, it is:

• Žárovka = subject
• je = verb
• v pokoji = location phrase

Because the preposition v meaning in requires the locative case when it shows location.

The basic dictionary form is:

• pokoj = room

But after v for static location, it changes to:

• v pokoji = in the room

So:

• pokoj = base form
• v pokoji = locative singular

This is very common in Czech: nouns change their endings depending on their role in the sentence.

Pokoji is in the locative singular.

It is used because v with the meaning in/inside normally takes the locative when you are describing where something is.

So:

• v pokoji = in the room
• v domě = in the house
• v autě = in the car

A useful contrast:

• v pokoji = in the room
• do pokoje = into the room

So locative is used for location, while do + genitive is used for movement into something.

Czech does not have articles like English a/an and the.

So Žárovka je v pokoji could mean:

• The light bulb is in the room
• A light bulb is in the room

Which one is meant depends on the context.

English speakers often look for a direct equivalent of the or a, but Czech usually leaves that unstated.

Yes, it matters.

• žárovka is feminine
• pokoj is masculine inanimate

Gender affects things like:

• adjective endings
• pronouns
• some numeral forms
• certain past tense forms

For example:

• Ta žárovka je nová. = That light bulb is new.
• Ten pokoj je malý. = That room is small.

So learning the gender of nouns is very important in Czech.

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

The original sentence:

• Žárovka je v pokoji.

Another common version:

• V pokoji je žárovka.

Both are grammatical, but the emphasis changes a little.

• Žárovka je v pokoji.
  Focuses more on the light bulb
• V pokoji je žárovka.
  Feels more like There is a light bulb in the room or emphasizes the location first

Czech often uses word order to show what is already known and what is new information.

In a normal full sentence, you should keep je.

• Žárovka je v pokoji. = correct full sentence

If you remove it:

• Žárovka v pokoji

that sounds incomplete in standard Czech, like a note, label, or fragment rather than a normal sentence.

So unlike in some other Slavic languages, the present tense of být (to be) is normally expressed in Czech.

For the basic physical meaning in the room, v pokoji is the normal choice.

• Žárovka je v pokoji. = The light bulb is in the room.

Na pokoji exists, but it is used in different contexts and often has a different feel. For example, it can be used in places like hospitals, hotels, dorms, or in idiomatic expressions.

So for a simple object being located inside a room, use:

• v pokoji

You would usually say:

• do pokoje = into the room

So compare:

• Žárovka je v pokoji. = The light bulb is in the room.
• Jdu do pokoje. = I am going into the room.

This is an important Czech pattern:

• v + locative = in, inside, at a location
• do + genitive = into, movement toward the inside

A yes/no question can be made very simply.

Common version:

• Je žárovka v pokoji? = Is the light bulb in the room?

You may also hear the same words with question intonation in speech:

• Žárovka je v pokoji?

But in standard written Czech, starting with the verb is very common for yes/no questions:

• Je žárovka v pokoji?