V grilu je dřevěné uhlí a briketa.

Because v means in, and after v Czech normally uses the locative case when you are talking about location.

• dictionary form: gril
• after v: v grilu = in the grill

So grilu is the locative singular form of gril.

Both v and na can be used with grills, but they mean different things.

• v grilu = inside the grill
• na grilu = on the grill / on the grill grate

Since charcoal and a briquette are physically inside the grill, v grilu is the natural choice here.

This is a very common question. In Czech, sentences like this often work like English there is/there are sentences: they present what is somewhere.

So V grilu je dřevěné uhlí a briketa is a natural presentational sentence: In the grill, there is charcoal and a briquette.

Why singular je?

• the verb comes before the things being listed
• dřevěné uhlí is a singular mass noun
• in this type of sentence, Czech often uses singular je

You may also hear plural jsou in other contexts, especially if the subject comes first:

• Dřevěné uhlí a briketa jsou v grilu.

That version is also grammatical, but it shifts the emphasis a bit.

Yes. Czech word order is flexible.

Compare:

• V grilu je dřevěné uhlí a briketa.
  Focuses first on where the things are.

• Dřevěné uhlí a briketa jsou v grilu.
  Focuses first on what the things are.

The original sentence sounds like introducing the contents of the grill.

Because dřevěné is an adjective agreeing with uhlí.

• uhlí is neuter
• it is singular
• here it is in the nominative form

So the adjective must match it:

• dřevěné uhlí = charcoal

If it described briketa instead, it would be:

• dřevěná briketa

because briketa is feminine.

It is both understandable literally and a standard everyday term.

• dřevěný = wooden / made from wood
• uhlí = coal / charcoal

But dřevěné uhlí specifically means charcoal: fuel made by burning wood in a controlled way.

So although the literal parts are clear, the whole phrase is best learned as the normal Czech expression for charcoal.

Here it is singular.

That can feel strange to English speakers because charcoal may consist of many pieces, but Czech treats uhlí as a mass noun, like English coal or charcoal.

So grammatically it is singular even if there is a lot of it.

That is one reason why je sounds natural in this sentence.

They are:

• gril — masculine inanimate
• uhlí — neuter
• briketa — feminine

This matters because Czech adjectives and some verb forms change depending on gender and number.

For example:

• dřevěné uhlí — neuter singular
• dřevěná briketa — feminine singular

Briketa means a briquette: a compressed block of fuel.

In this sentence:

• dřevěné uhlí = loose charcoal
• briketa = a single briquette

So the sentence mentions two kinds/forms of fuel in the grill.

Because Czech does not have articles.

English says:

• in the grill
• a briquette

Czech usually expresses that meaning without separate words for a/an/the:

• v grilu
• briketa

Whether something is definite or indefinite is usually understood from context.

Dřevěné is one of the harder words here.

A rough guide:

• stress is on the first syllable
• it sounds approximately like DŘE-vě-né

The hardest part is ř, a special Czech sound. It is often described as something between r and zh. English does not have an exact equivalent.

A very rough approximation is:

• drzheh-vyeh-nay

That is not perfect, but it can help you get started. The real Czech ř takes practice.