Podpalovač je pod roštem; stačí, když rozpálíte dřevěné uhlí.

Here podpalovač means an object: a firelighter / fire starter used to help ignite charcoal.

Even though the ending -ač can sometimes refer to a person, in this sentence it is a masculine inanimate noun. So it does not mean an arsonist here.

Because pod can take different cases depending on meaning:

• pod + instrumental = location (under something, already there)
• pod + accusative = movement (to under something)

So:

• je pod roštem = it is under the grate → location
• If you were saying put it under the grate, then you would use the accusative:
  • Dejte ho pod rošt.

This is a very common pattern with Czech prepositions.

Roštem is the instrumental singular of rošt.

Basic forms:

• nominative: rošt
• instrumental: roštem

It appears in the instrumental because of pod in a location meaning: pod roštem = under the grate.

Rošt means a grate, rack, or grill grate, depending on context.

In this sentence, it is most likely the metal grate in a grill or barbecue. So pod roštem means the firelighter is placed underneath the part where the charcoal or food sits.

Stačí means it is enough, it suffices, or all you need to do is...

Czech often leaves out a dummy subject like English it. So:

• Stačí. = That’s enough / It’s enough.
• Stačí, když... = It’s enough if... / All you need to do is...

So Czech uses just the verb, while English usually needs it.

Stačí, když... is a very common Czech structure meaning:

• it’s enough if...
• all you need to do is...
• you just need to...

So:

• Stačí, když rozpálíte dřevěné uhlí.

literally works like:

• It is enough if you light/get the charcoal burning.

This pattern is idiomatic and very useful in everyday Czech.

Yes—good question. Když often means when, but in the structure stačí, když..., it is often best translated as if or when/once you just...

So in this sentence, když does not have a strong time meaning like when in a story. It is part of the fixed pattern stačí, když...

Compare:

• Když přijdu domů, zavolám ti. = When I get home, I’ll call you.
• Stačí, když zavoláš. = It’s enough if you call / You just need to call.

Rozpálíte is 2nd person plural of the verb rozpálit.

It can mean:

• you (plural) will get burning / heat up / ignite
• or you (formal singular) will get burning / heat up / ignite

So this form can address:

1. more than one person, or
2. one person formally (vy form)

If speaking to one person informally, Czech would use:

• rozpálíš

Because rozpálit is a perfective verb.

In Czech, perfective verbs use their present-tense forms to express future meaning.

So:

• rozpálíte literally looks present by form,
• but it means you will ignite / you get burning in actual usage.

This is normal in Czech.

Compare:

• děláte (imperfective) = you are doing / you do
• uděláte (perfective) = you will do / you get done

Likewise:

• pálíte = you are burning / heating
• rozpálíte = you will ignite / get very hot / make burn strongly

Very roughly:

• pálit = to burn, to heat, sometimes to sting
• rozpálit = to set blazing, to heat up strongly, to get properly burning

The prefix roz- often adds a sense of spreading out, starting fully, or getting into full action.

So here rozpálíte dřevěné uhlí suggests not just touching the charcoal with a flame, but getting it properly lit and burning well.

Yes, uhlí by itself often means coal. But dřevěné uhlí specifically means charcoal.

So:

• uhlí = coal
• dřevěné uhlí = charcoal

Literally, dřevěné means wooden / made from wood, so dřevěné uhlí is coal-like fuel made from wood: charcoal.

Here dřevěné uhlí is in the accusative singular as the direct object of rozpálíte.

But there is an important detail:

• uhlí is a neuter noun
• for many neuter inanimate nouns, the nominative and accusative are the same

So:

• nominative: dřevěné uhlí
• accusative: dřevěné uhlí

The adjective dřevěné agrees with uhlí in gender, number, and case.

No.

• podpalovač = firelighter / fire starter
• zapalovač = lighter (the small device used to make a flame)

So in a grilling context, podpalovač is the material that helps the charcoal catch fire, while zapalovač is the tool you might use to light it.

The semicolon separates two closely related parts:

• Podpalovač je pod roštem
• stačí, když rozpálíte dřevěné uhlí

It works a bit like a stronger comma or a softer full stop. It helps show that the second part explains or complements the first.

A full stop would also be possible in many contexts:

• Podpalovač je pod roštem. Stačí, když rozpálíte dřevěné uhlí.

Because když rozpálíte dřevěné uhlí is a subordinate clause.

Czech normally separates subordinate clauses with a comma, so:

• Stačí, když...

This is standard Czech punctuation.

Yes. Czech word order is flexible, although the original is natural.

For example, you could also say:

• Pod roštem je podpalovač.
• Dřevěné uhlí stačí rozpálit.
• Stačí rozpálit dřevěné uhlí.

These versions shift emphasis slightly:

• Pod roštem je podpalovač emphasizes under the grate
• Stačí rozpálit dřevěné uhlí is a more compact way to say you just need to get the charcoal burning

The original sentence sounds natural and informative, especially in instructions.

Because it uses rozpálíte, it is grammatically either:

• plural you, or
• formal singular you

In instructions, Czech often uses this kind of form to sound neutral and polite, especially in manuals, packaging, or public instructions.

A more informal singular version would be:

• Podpalovač je pod roštem; stačí, když rozpálíš dřevěné uhlí.

But that would sound much more personal and less like a general instruction.