Mám potvrzení o platbě, takže dnes napíšu odvolání.

Because Czech uses the verb mít (to have) in exactly the same kind of way as English here: Mám potvrzení = I have a confirmation / receipt.

• mám = I have
• jsem = I am

So:

• Mám potvrzení = I have a confirmation
• Jsem potvrzení would mean I am a confirmation, which makes no sense here.

Potvrzení means confirmation, certificate, or receipt/proof, depending on context.

In Mám potvrzení o platbě, it most naturally means:

• proof of payment
• payment confirmation
• sometimes receipt of payment

So it is not necessarily a shop receipt specifically; it is any document or evidence confirming that the payment was made.

Also, potvrzení is a neuter noun.

Platbě is in the locative case.

The preposition o often means about / concerning, and when it has that meaning, it is followed by the locative:

• o platbě = about the payment
• literally: confirmation about the payment

This is a very common Czech pattern:

• kniha o Praze = a book about Prague
• zpráva o nehodě = a report about the accident
• potvrzení o platbě = confirmation of/about payment

So although English says of payment, Czech uses o + locative here.

Because platba is being declined into the locative singular after o.

The basic form is:

• platba = payment

After o, it changes:

• o platbě = about the payment

This is a normal declension pattern for many feminine nouns ending in -a.

A few examples:

• škola → o škole
• smlouva → o smlouvě
• platba → o platbě

So platbě is not a different word; it is just the correct case form of platba.

This is about aspect, which is very important in Czech.

• psát = to write (imperfective)
• napsat = to write / to complete writing (perfective)

So:

• píšu = I am writing / I write
• napíšu = I will write / I will get it written

In this sentence, dnes napíšu odvolání means the speaker expects to write and complete the appeal today.

Because napsat is perfective, its present-tense forms often have future meaning:

• napíšu literally looks like present form, but means I will write

If you said dnes píšu odvolání, it would sound more like:

• Today I’m writing an appeal
• focusing on the activity, not necessarily its completion

Yes. With perfective verbs, Czech present forms usually express the future.

So:

• napíšu = I will write
• udělám = I will do
• pošlu = I will send

This is a key Czech grammar point:

• imperfective verb → future usually formed with budu + infinitive
  • budu psát = I will be writing / I will write
• perfective verb → simple present form has future meaning
  • napíšu = I will write (and finish it)

So dnes napíšu odvolání is completely normal Czech.

Here odvolání means an appeal, especially in an official, legal, or administrative sense.

So the sentence suggests something like:

• the speaker has proof of payment
• therefore they will now write an official appeal/challenge/request for reconsideration

Be careful: odvolání can have different meanings depending on context, for example:

• appeal (legal/administrative)
• recall or dismissal/removal from office in some contexts

But in this sentence, appeal is clearly the intended meaning.

It is in the accusative singular, but for many neuter nouns, the accusative singular is the same as the nominative singular.

So:

• odvolání = nominative singular
• odvolání = accusative singular as well

Here it is the direct object of napíšu:

• napíšu co? = odvolání

That is why the form does not change.

The same thing happens with many neuter nouns:

• auto → mám auto
• potvrzení → mám potvrzení
• odvolání → napíšu odvolání

Takže means so, therefore, or and so.

It connects the two parts of the sentence:

• Mám potvrzení o platbě = I have proof of payment
• takže dnes napíšu odvolání = so today I’ll write the appeal

The comma is normal because takže introduces the result/consequence of the first clause.

This is similar to English punctuation in many cases:

• I have proof of payment, so I’ll write the appeal today.

In Czech, commas are used quite regularly before connecting words like this.

Yes. Czech word order is flexible, and changing it often changes emphasis rather than basic meaning.

The original sentence:

• Mám potvrzení o platbě, takže dnes napíšu odvolání.

A few possible variations:

• Dnes napíšu odvolání, protože mám potvrzení o platbě.
  • I’ll write the appeal today because I have proof of payment.
• Odvolání dnes napíšu, protože mám potvrzení o platbě.
  • puts more emphasis on the appeal
• Mám potvrzení o platbě, takže odvolání dnes napíšu.
  • emphasizes that the appeal is what will be written today

The original version sounds natural and neutral.

Because dnes (today) is an adverb, and in Czech adverbs of time often appear early in the clause, often before the verb.

So:

• takže dnes napíšu odvolání = so today I will write the appeal

This is very natural Czech word order.

You could also say:

• takže napíšu odvolání dnes

but that usually sounds more marked or contrastive, as if emphasizing today specifically.

So the original sentence has the most natural neutral order.

Czech has no articles.

So nouns like:

• potvrzení
• platba
• odvolání

do not need words equivalent to a, an, or the.

Whether English translation uses a, the, or no article at all depends on context:

• Mám potvrzení o platbě
  could be:

  • I have a payment confirmation
  • I have the proof of payment
  • I have proof of payment

• dnes napíšu odvolání could be:

  • today I’ll write an appeal
  • today I’ll write the appeal

Czech leaves that distinction to context.

It is neutral in grammar, but the vocabulary is somewhat formal/administrative because of words like:

• potvrzení o platbě
• odvolání

These are common in official or bureaucratic situations.

The sentence itself is not especially stiff or unnatural, though. A normal speaker could absolutely say it in everyday life if they were talking about a real administrative problem.

So:

• grammar/register: neutral
• topic/vocabulary: official/administrative

In Czech, the main rule is simple: stress usually falls on the first syllable of each word.

So roughly:

• MÁM
• PO-tvr-ze-ní
• o PLAT-bě
• TAK-že
• DNES
• NA-pí-šu
• od-VO-lá-ní → careful: word stress is still on the first syllable: OD-vo-lá-ní

So the sentence is pronounced with first-syllable stress throughout.

One useful point: Czech stress is regular, unlike English, so once you learn the rule, pronunciation becomes much easier.