V troubě je teplá večeře.

Because v means in, and when it expresses location in Czech, it normally takes the locative case.

• dictionary form: trouba = oven
• locative singular: (v) troubě = in the oven

So:

• v troubě = in the oven

A useful rule:

• v + locative = in/inside a place
• compare with motion:
  • do trouby = into the oven

So V troubě je... means something is already located there, not moving there.

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

The basic structure is:

• večeře je = dinner is

So in V troubě je teplá večeře, the thing that is somewhere is teplá večeře.

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

Here:

• večeře is a feminine singular noun
• so the adjective teplý changes to teplá

That gives:

• teplá večeře = warm dinner

Agreement here is:

• gender: feminine
• number: singular
• case: nominative

Je is the 3rd person singular present tense of být = to be.

So:

• je = is

The sentence literally works like:

• V troubě je teplá večeře.
• In the oven is a warm dinner.

Natural English would usually be:

• There is a warm dinner in the oven.
• or A warm dinner is in the oven.

Czech does not need a dummy word like English there in there is.

No, Czech word order is quite flexible. The sentence V troubě je teplá večeře is perfectly natural, but other orders are also possible.

For example:

• Teplá večeře je v troubě.
  Focuses more on the warm dinner
• V troubě je teplá večeře.
  Often presents the location first
• Je v troubě teplá večeře?
  This can be a question: Is there a warm dinner in the oven?

The different orders usually change emphasis or information structure, not the core meaning.

Because Czech has no articles like English a/an/the.

So teplá večeře can mean:

• a warm dinner
• the warm dinner

Which one is meant depends on the context.

That is very normal in Czech.

Because an oven is treated as an enclosed space, so Czech uses v = in.

• v troubě = in the oven

By contrast, na is often used for a surface or certain set expressions:

• na stole = on the table

So:

• food is v troubě
• a plate might be na stole

Usually teplý / teplá / teplé means warm.

So teplá večeře is most naturally a warm dinner.

If you want to stress hot, Czech often uses:

• horký = hot

So:

• teplá večeře = warm dinner
• horká večeře = hot dinner

In everyday speech, though, teplá can still sound perfectly natural for food that is pleasantly heated.

A rough guide:

• troubě ≈ TROH-byeh
• večeře ≈ VEH-che-rzheh

A few important points:

• ou in Czech is a real diphthong, roughly like oh + oo
• ě often affects the sound before it; in bě, it sounds roughly like bye
• č is like ch in check
• ř is the famous Czech sound: something like a mix of r and zh. English speakers usually need practice with it.

You do not need a perfect ř right away to be understood.

Yes. Besides oven, trouba can also be a colloquial insult meaning something like idiot or fool.

But in this sentence, because of v troubě and the context of dinner, it clearly means oven.

So here there is no ambiguity for a native speaker.

In normal standard Czech, je is natural and expected in this sentence.

• V troubě je teplá večeře. = standard, complete

In some very informal styles or headlines, forms of to be can sometimes be omitted, but for a learner, you should treat je as necessary here.

So the safe version is:

• V troubě je teplá večeře.