Závazek skončí zítra, ale mobilní operátor ho chce prodloužit.

In this context, závazek usually means a commitment or contractual obligation — especially the fixed period you are tied to with a mobile provider.

So with a mobile operator, závazek often refers to the minimum contract term rather than the whole contract document itself.

Because skončit is a perfective verb.

In Czech, perfective verbs use their present-tense forms to talk about a completed future event. So:

• skončí = will end
• not normally is ending right now

This is very common in Czech and often surprises English speakers, because English usually needs will for the future.

The main difference is aspect:

• skončí = from skončit = perfective
• končí = from končit = imperfective

Very roughly:

• skončí focuses on the event being completed
• končí focuses on the process or repeated/habitual action

So:

• Závazek skončí zítra. = The commitment will end tomorrow.
• Závazek končí. = The commitment is ending / comes to an end.

In your sentence, skončí is natural because the speaker is talking about the contract reaching its endpoint.

Because Czech does not always need one.

For imperfective verbs, Czech often forms the future with být + infinitive:

• bude dělat = will do

But for perfective verbs, the present form already has future meaning:

• udělá = will do
• skončí = will end

So the future is expressed through the verb’s aspect, not always with a separate helping word.

Because zítra is an adverb, meaning tomorrow.

Just like English says tomorrow without a preposition, Czech does the same:

• zítra = tomorrow
• dnes = today
• včera = yesterday

So Závazek skončí zítra is perfectly natural.

Ho is a short unstressed form of the 3rd person singular accusative pronoun.

It can mean:

• him
• it

Here it refers back to závazek, which is a masculine singular noun, so English translates it as it:

• mobilní operátor ho chce prodloužit = the mobile operator wants to extend it

So even though ho may look like him, in Czech it is also used for masculine nouns that English would call it.

Both are possible as accusative forms of he/it, but ho is much more common in everyday Czech as the short unstressed form.

• ho = short, common, clitic form
• jej = fuller, more formal or emphatic

In an ordinary sentence like this, ho is the natural choice.

Because ho is a clitic — a short unstressed word that tends to go in the second position of its clause.

In the clause:

ale mobilní operátor ho chce prodloužit

the first main element is mobilní operátor, so ho comes right after it.

This is a very important Czech word-order rule. Short words like ho, mu, se, si often appear early in the sentence, even if English would place them later.

So:

• mobilní operátor ho chce prodloužit = natural
• mobilní operátor chce ho prodloužit = much less natural

Because it depends on chce:

• chce = wants
• prodloužit = to extend

Just like English says wants to extend, Czech says chce prodloužit.

After chtít (to want), Czech normally uses an infinitive if the subject wants to do an action.

Again, this is about aspect.

• prodloužit = perfective = to extend, to make longer, seen as a completed action
• prodlužovat = imperfective = to be extending / to extend repeatedly / to keep extending

In this sentence, the operator wants to carry out one concrete action: extend the commitment. So prodloužit is the natural choice.

If you used prodlužovat, it would sound more like an ongoing or repeated process.

The main ones are:

• závazek — nominative singular
  It is the subject of skončí.

• mobilní operátor — nominative singular
  It is the subject of chce.

• ho — accusative singular
  It is the direct object of prodloužit.

So the sentence structure is basically:

• subject + verb + time
• but + subject + object + verb + infinitive

Yes, normally it is.

Ale means but, and here it joins two independent clauses:

• Závazek skončí zítra
• ale mobilní operátor ho chce prodloužit

In Czech, a comma is usually written before coordinating conjunctions like ale when they connect full clauses.

Yes, Czech word order is flexible, but not completely free.

This sentence has a very neutral order:

Závazek skončí zítra, ale mobilní operátor ho chce prodloužit.

You can move elements for emphasis, but you still have to respect rules like clitic placement. For example:

• Závazek skončí zítra, ale ho mobilní operátor chce prodloužit. — unnatural
• Závazek skončí zítra, ale mobilní operátor ho chce prodloužit. — normal
• Závazek skončí zítra, ale prodloužit ho chce mobilní operátor. — possible, but more marked/emphatic

So yes, the order can change, but the original sentence is the most neutral and natural version.