Сухие дрова быстро горят.

Because it has to agree with дрова in number and case.

• дрова is plural
• here it is in the nominative plural because it is the subject
• so the adjective must also be nominative plural

That is why you get:

• masculine singular: сухой
• feminine singular: сухая
• neuter singular: сухое
• plural: сухие

So сухие дрова = dry firewood / dry logs.

Russian дрова is a plural-only noun in normal usage. This is called pluralia tantum.

So even when English uses an uncountable singular idea like firewood, Russian treats дрова as grammatically plural:

• дрова горят
• сухие дрова
• много дров

You normally do not use a singular form like дрово.

It is nominative plural.

Why?

Because дрова is the subject of the sentence — the thing doing the action of burning.

So:

• Сухие дрова = the subject
• быстро = adverb
• горят = verb

Because the subject is plural.

The verb гореть in the present tense changes for number:

• я горю
• ты горишь
• он / она горит
• мы горим
• вы горите
• они горят

Since дрова is grammatically plural, Russian uses the third person plural form:

• дрова горят

not

• дрова горит

Here горят is from the imperfective verb гореть.

It can mean:

• burn
• are burning

depending on context.

In this sentence, it can express either:

1. a general fact: dry firewood burns quickly
2. something happening right now: the dry firewood is burning quickly

Because it is imperfective, it focuses on the process, not on completion.

If you wanted the idea of burn up completely, Russian might use a different verb or a prefixed form depending on context.

Быстро is an adverb, meaning quickly / fast.

It describes the verb горят — in other words, it tells you how the wood burns.

Compare:

• быстрый = fast, quick (adjective)
• быстро = quickly, fast (adverb)

So:

• быстрый огонь = a fast-spreading fire
• дрова быстро горят = the firewood burns quickly

Yes. Russian word order is fairly flexible.

The neutral order here is:

• Сухие дрова быстро горят.

But you could also say:

• Дрова быстро горят.
• Быстро горят сухие дрова.
• Сухие дрова горят быстро.

The basic meaning stays similar, but the emphasis changes:

• Сухие дрова быстро горят = neutral statement
• Быстро горят сухие дрова = stronger focus on burn quickly
• Сухие дрова горят быстро = often sounds like the speed is being emphasized at the end

Russian has no articles.

So дрова can mean:

• the firewood
• some firewood
• firewood

The exact meaning depends on context.

That is normal in Russian. Learners often have to get used to understanding definiteness from the situation instead of from words like the or a.

A natural pronunciation is:

сухи́е дрова́ бы́стро горя́т

Stress:

• сухи́е
• дрова́
• бы́стро
• горя́т

A rough English-style approximation would be:

• soo-KHEE-yeh
• dra-VAH
• BIS-tra
• ga-RYAT

But it is better to listen to native audio, especially for:

• the Russian р
• the vowel reduction in unstressed syllables
• the soft consonants

Yes, it is very natural.

Russian often uses an adjective + noun structure just like English:

• сухие дрова = dry firewood
• мокрые дрова = wet firewood
• берёзовые дрова = birch firewood

So this phrase is completely standard and idiomatic.

Yes.

Russian present tense often covers both:

• right now
• general/habitual truth

So Сухие дрова быстро горят can mean:

• Dry firewood burns quickly
  or
• The dry firewood is burning quickly

Context tells you which reading is intended. Without extra context, many people will understand it as a general fact.