Svědek čeká v druhé místnosti.

A rough English-friendly pronunciation is:

• Svědek → SVYE-dek
• čeká → CHEH-kaa
• v druhé → v DROO-hay
• místnosti → MEEST-nyos-tee

A few useful notes:

• Czech stress is usually on the first syllable of each word.
• ě often makes the previous consonant sound softer; in svě, it sounds roughly like svye.
• á and í are long vowels. They are held a little longer than short vowels.

Svědek is the subject of the sentence, so it is in the nominative singular.

Grammar details:

• dictionary form: svědek
• meaning: witness
• gender: masculine animate
• number: singular

It is masculine animate because it refers to a person.

Čeká is the 3rd person singular present tense form of čekat (to wait).

So:

• já čekám = I wait / I am waiting
• ty čekáš = you wait / you are waiting
• on/ona čeká = he/she waits / is waiting

In this sentence, svědek čeká means the witness waits or the witness is waiting.

It can mean either one, depending on context.

Czech present tense often covers both:

• he waits
• he is waiting

So Svědek čeká can be understood as either The witness waits or The witness is waiting. In normal English, is waiting is often the more natural translation.

Because v means in, and when it shows location, it usually takes the locative case.

Here the phrase means in the second room, so:

• v = in
• druhé místnosti = locative singular

If you are talking about being somewhere, v + locative is very common.

Because adjectives in Czech must agree with the noun they describe.

The noun here is místnost:

• gender: feminine
• number: singular
• case: locative

So the adjective druhý (second) changes to match it:

• nominative feminine singular: druhá
• locative feminine singular: druhé

That is why we get v druhé místnosti.

Because místnost is in the locative singular after v.

Its basic form is:

• místnost = room

But after v when talking about location:

• v místnosti = in the room

So in this sentence:

• v druhé místnosti = in the second room

This is a normal case change in Czech noun declension.

Here it means second.

The adjective druhý usually means second in an ordered sense:

• první = first
• druhý = second
• třetí = third

So v druhé místnosti means in the second room, not in another room.

If you wanted to say another room, Czech would usually use a different word, such as jiná in the right form.

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

So Czech often leaves that idea to context.

For example:

• svědek can mean a witness or the witness
• místnost can mean a room or the room

In this sentence, the intended meaning is understood from context, not from an article.

No, Czech word order is fairly flexible.

This sentence is a neutral, natural order:

• Svědek čeká v druhé místnosti.
• The witness is waiting in the second room.

But other orders are possible for emphasis, for example:

• V druhé místnosti čeká svědek.
  = In the second room, a witness is waiting.
• Čeká svědek v druhé místnosti?
  = Is the witness waiting in the second room?

The basic meaning stays similar, but the emphasis can change.

Svědek is in the nominative case because it is the subject of the sentence — the one performing the action.

In Svědek čeká:

• svědek = who is doing the waiting
• therefore it is nominative

This is the normal case for the subject of a sentence in Czech.