Zákazník vypověděl smlouvu na dobu neurčitou a výpovědní lhůta už běží.

It means gave notice on / terminated the contract. In legal or business Czech, vypovědět smlouvu is a standard expression for ending a contract by notice.

It is often close to cancelled the contract, but it is a bit more specific:

• vypovědět smlouvu = terminate it by giving notice
• zrušit smlouvu = cancel / annul the contract
• ukončit smlouvu = end the contract, more general

So in this sentence, the idea is not just that the contract stopped instantly, but that it was terminated in a way that starts a notice period.

Vypověděl is the correct masculine singular past-tense form of the verb vypovědět.

Breakdown:

• infinitive: vypovědět
• past masculine singular: vypověděl
• past feminine singular: vypověděla
• past neuter singular: vypovědělo
• past plural masculine animate: vypověděli

It agrees with zákazník, which is masculine singular, so vypověděl is required.

Because smlouvu is the direct object of vypověděl, so it is in the accusative singular.

The noun is:

• nominative: smlouva
• accusative: smlouvu

So:

• smlouva = a contract
• vypovědět smlouvu = to terminate a contract

This is very normal in Czech: verbs often require the thing affected to be in the accusative.

Literally, it means for an indefinite period.

This is a fixed Czech expression used for contracts, employment, rentals, subscriptions, etc.

Structure:

• na = for
• dobu = period / time span, accusative of doba
• neurčitou = indefinite, also accusative feminine singular to match dobu

So:

• smlouva na dobu určitou = a fixed-term contract
• smlouva na dobu neurčitou = an indefinite-term contract

English often says open-ended contract or contract for an indefinite period.

Because the preposition na here governs the accusative when it means something like for a period of.

The noun phrase is:

• doba neurčitá = an indefinite period

But after na, it becomes:

• na dobu neurčitou

Both the noun and the adjective must match in case, gender, and number:

• doba → dobu
• neurčitá → neurčitou

Výpovědní lhůta means notice period.

The two words are:

• výpovědní = relating to notice / termination by notice
• lhůta = deadline, period, time limit

Together, výpovědní lhůta is the period between giving notice and the actual end of the contract.

This is standard legal/business vocabulary in Czech.

Yes, literally běžet means to run, but Czech uses it idiomatically for time periods, deadlines, and processes.

So:

• lhůta běží = the period is running
• natural English translation: the notice period is underway / has started / is already running

Czech often uses běžet where English might say:

• be in progress
• be underway
• run
• count down, depending on context

So this is a normal and common expression.

Už means already.

In this sentence, it shows that the notice period has already started:

• výpovědní lhůta běží = the notice period is running
• výpovědní lhůta už běží = the notice period is already running

It gives a sense that this is no longer just a future possibility; the process is now in progress.

Both are possible, but they sound slightly different in emphasis.

• Výpovědní lhůta už běží = neutral, natural word order
• Už výpovědní lhůta běží = stronger emphasis on already

Czech word order is flexible, and speakers move words around to highlight different parts of the message. In a neutral statement, the version in your sentence is very natural.

Yes. A simply connects the two clauses:

• Zákazník vypověděl smlouvu na dobu neurčitou
• a výpovědní lhůta už běží

So it means:

• The customer terminated the indefinite-term contract, and the notice period is already running.

No special meaning here beyond a normal connection between two statements.

Czech often leaves things more implicit than English does.

In English, you might naturally say:

• The customer terminated the contract, and the notice period is already running.

Czech does not need articles like the or a, because Czech has no articles. The meaning is understood from context.

Also, Czech often does not add possessives unless they are needed. So smlouvu can mean the contract / their contract, depending on context.

Usually zákazník means customer. In some business contexts, English might choose client instead, depending on the relationship.

Very roughly:

• zákazník = customer
• klient = client

But in real-life usage, the translation can depend on the company or legal context. If this is about telecoms, insurance, or subscriptions, English might sometimes prefer customer, sometimes client, even though the Czech says zákazník.

Yes, vypovědět is a perfective verb, and that matters a lot.

Perfective means the action is seen as completed:

• zákazník vypověděl smlouvu = the customer has given notice / terminated the contract

The imperfective partner is often vypovídat, though in practice the perfective form is especially common for this legal action.

Why perfective fits here:

• the act of giving notice happened and is complete
• as a result, the notice period is now running

So the sentence presents a completed action followed by its ongoing consequence.

Then the past-tense verb would change to agree with the feminine subject:

• Zákaznice vypověděla smlouvu na dobu neurčitou a výpovědní lhůta už běží.

Compare:

• masculine: zákazník vypověděl
• feminine: zákaznice vypověděla

The second clause stays the same, because výpovědní lhůta is still the subject there.

Yes, definitely. It is a very common fixed phrase.

Useful pair:

• smlouva na dobu určitou = fixed-term contract
• smlouva na dobu neurčitou = indefinite-term contract

You can also see the same pattern with other nouns:

• pracovní poměr na dobu neurčitou = employment for an indefinite period
• nájem na dobu určitou = tenancy for a fixed period

So it is worth memorizing the whole pattern na dobu určitou / neurčitou.