Jestli máte žízeň, přinesu vám sklenici vody; vadí vám, když nebude studená?

Jestli means if / whether.

In Jestli máte žízeň..., it introduces a straightforward condition: If you are thirsty...

Later, když appears in vadí vám, když nebude studená? After verbs like vadit (to bother / to mind), Czech very often uses když in the sense of if/when:

• Vadí vám, když otevřu okno? = Do you mind if I open the window?
• Vadí ti, když přijdu později? = Do you mind if I come later?

So the two words overlap somewhat, but in this sentence each one is in a very natural place:

• jestli = regular if
• když = if/when after vadit

Because Czech expresses this idea idiomatically as have thirst, not be thirsty.

• mít žízeň = to be thirsty
• literally: to have thirst

This is just the normal Czech expression, much like:

• mít hlad = to be hungry (literally have hunger)
• mít strach = to be afraid (literally have fear)

So máte žízeň is the standard way to say you are thirsty.

It can be either:

1. plural you: talking to several people
2. formal singular you: talking politely to one person

So this sentence could mean either:

• speaking politely to one person, or
• speaking to multiple people

That is very common in Czech. The forms are the same:

• máte = you have
• vám = to you / you in the dative

If the speaker were talking informally to one person, the sentence would use máš and ti instead:

• Jestli máš žízeň, přinesu ti sklenici vody; vadí ti, když nebude studená?

Because sklenici is the accusative singular form of sklenice.

Here it is the direct object of přinesu (I will bring), so accusative is needed:

• přinesu sklenici = I’ll bring a glass

Then vody is in the genitive, because Czech often uses the pattern:

container/amount noun + genitive

• sklenice vody = a glass of water
• šálek čaje = a cup of tea
• láhev vína = a bottle of wine

So:

• dictionary form: sklenice
• in this sentence: sklenici because it is the object

Because after words for containers, amounts, and measures, Czech commonly puts the thing contained in the genitive.

So:

• sklenice vody = a glass of water
• literally: glass of water

This is a very common pattern. More examples:

• talíř polévky = a plate/bowl of soup
• kus chleba = a piece of bread
• hrnek kávy = a mug of coffee

In your sentence, sklenici changes case because of its role in the sentence, but vody stays genitive because it depends on glass.

Both instances are dative.

1. přinesu vám sklenici vody
   = I’ll bring you a glass of water
   Here vám means to you / for you.

2. vadí vám...
   = does it bother you / do you mind...
   The verb vadit takes the person affected in the dative.

So in both places, vám is dative, but the role is slightly different:

• with přinést: recipient
• with vadit: the person to whom something is bothersome

Přinesu has a present-tense form, but because the verb is perfective, it refers to the future.

So:

• přinesu = I will bring

This is a key Czech pattern:

• imperfective present = true present / ongoing / habitual
• perfective present form = future meaning

Compare:

• nosím = I carry / I am carrying / I usually bring
• přinesu = I will bring (once, to completion)

Here the speaker means a single completed action: I’ll bring you a glass of water. That is why přinesu is used.

Because studená is feminine singular, agreeing with an understood feminine noun — most naturally voda.

So the idea is really:

• když voda nebude studená = if the water isn’t cold

But Czech often leaves out a noun when it is obvious from context. Since voda was just mentioned, it can be omitted.

That is why the adjective stays feminine singular:

• studená = feminine singular
• understood noun: voda

English uses it, but Czech still makes the adjective agree with the implied noun behind that it.

Literally, vadí vám? means something like Does it bother you?

In natural English, that often becomes:

• Do you mind...?
• Would it bother you if...?

So:

• Vadí vám, když nebude studená? = Do you mind if it isn’t cold? = Would it bother you if it wasn’t cold?

A useful pattern to remember is:

• Vadí ti/vám, když... ? = Do you mind if/when... ?

Examples:

• Vadí ti, když zavřu dveře? = Do you mind if I close the door?
• Vadí vám, když si sednu? = Do you mind if I sit down?

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

For example, you could also say:

• Přinesu vám sklenici vody, jestli máte žízeň.

That still means the same thing.

However, short unstressed words like vám tend to appear early in the clause, often in the second position area. That is why:

• přinesu vám sklenici vody sounds more natural than
• přinesu sklenici vody vám unless vám is specially emphasized

Likewise:

• vadí vám, když... is the normal order

So yes, the order can move for emphasis or style, but the sentence as given is very natural.

Yes. To one person informally, you would normally use ty-forms:

• Jestli máš žízeň, přinesu ti sklenici vody; vadí ti, když nebude studená?

Changes:

• máte → máš
• vám → ti
• vadí vám → vadí ti

So the original sentence sounds either:

• polite to one person, or
• addressed to several people

The informal version is for one person you know well.