Když je moje dcera žíznivá, přinese si z kuchyně sklenici vody.

Here když means when or, even more naturally in English, whenever.

The sentence describes a repeated, typical situation:

• Když je moje dcera žíznivá... = When/Whenever my daughter is thirsty...

So this is not about one specific future event only. It is a general pattern: each time that condition happens, she gets water.

It is true that in informal Czech, když can sometimes be used where English would use if, but in this sentence the meaning is clearly when/whenever.

Because dcera is feminine singular, and the adjective has to agree with it.

• dcera = daughter, feminine
• žíznivá = thirsty, feminine singular
• masculine singular would be žíznivý

So:

• moje dcera je žíznivá = my daughter is thirsty
• můj syn je žíznivý = my son is thirsty

In this sentence, no. Czech normally uses být (to be) with predicate adjectives like žíznivá.

So:

• je žíznivá = is thirsty

You cannot normally just say:

• moje dcera žíznivá

That would sound incomplete in standard Czech. So je is necessary here.

Both are possible, and both mean my daughter.

• moje dcera = very common, neutral, natural in everyday speech
• má dcera = also correct, but can sound a bit more formal, literary, or sometimes slightly emphatic depending on context

For many learners, moje feels easier because it is very common in spoken Czech.

So this sentence could also be:

• Když je má dcera žíznivá, ...

But moje dcera is perfectly natural.

Si is a reflexive dative pronoun. Here it means something like for herself.

So:

• přinese si sklenici vody = she brings herself / gets herself a glass of water

It shows that she is doing the action for her own benefit.

Compare:

• přinese sklenici vody = she brings a glass of water
• přinese si sklenici vody = she brings herself a glass of water

In natural English, we often do not translate si word-for-word. We may simply say:

• she gets a glass of water
• she brings herself a glass of water

This is mainly a question of aspect.

• přinést → perfective
• přinášet / přinášet si → imperfective

Přinese presents the action as a completed whole: when she gets thirsty, she goes and fetches a glass of water. The focus is on the result of each individual event.

That is very natural in Czech in sentences like this, where one event regularly follows another.

A rough contrast:

• Když je žíznivá, přinese si sklenici vody.
  = each time, she goes and gets one; completed action

• Když je žíznivá, přináší si sklenici vody.
  = possible, but less natural here; it sounds more like focusing on the ongoing/repeated activity rather than each completed fetch

So přinese is used because Czech often prefers the perfective verb when describing what happens on each occasion.

Because in Czech, perfective verbs often use present-looking forms to express a future or completed-once meaning.

So although přinese has present-tense endings, it does not mean she is bringing right now. With a perfective verb, it means something more like:

• she will bring
• she will fetch
• in a general statement: she fetches / gets

In this sentence, English naturally uses the simple present because English often does that in when/whenever clauses and general truths:

• When my daughter is thirsty, she gets a glass of water.

So the forms do not match one-to-one between the two languages.

Because the preposition z means from/out of and it requires the genitive case.

• z = from
• kuchyně = kitchen
• z kuchyně = from the kitchen

A useful detail: with kuchyně, the genitive singular happens to look the same as the nominative singular:

• nominative: kuchyně
• genitive after z: kuchyně

So the form does not change in spelling here, but the case still changes grammatically.

Because two different case patterns are happening at the same time.

1. sklenici is accusative

It is the direct object of přinese si.

• nominative: sklenice
• accusative: sklenici

So:

• přinese si sklenici = she brings/gets a glass

2. vody is genitive

After a container or quantity noun, Czech often uses the genitive for the substance inside:

• sklenice vody = a glass of water
• literally: a glass of water where water is in the genitive

This is very common in Czech:

• šálek čaje = a cup of tea
• láhev vína = a bottle of wine
• kus chleba = a piece of bread

So sklenici vody is the normal way to say a glass of water.

Because Czech has no articles like English a and the.

So:

• sklenici vody can mean a glass of water
• in another context, it could also mean the glass of water

The exact meaning depends on context.

In this sentence, the natural English translation is a glass of water, because it is a general repeated action, not a specific previously mentioned glass.

Because Když je moje dcera žíznivá is a subordinate clause, and Czech normally separates subordinate clauses with a comma.

So the structure is:

• Když je moje dcera žíznivá, = subordinate clause
• přinese si z kuchyně sklenici vody. = main clause

This comma is required in standard Czech writing.

Yes. Czech word order is more flexible than English, because case endings show grammatical relationships.

The sentence as given is natural:

• Když je moje dcera žíznivá, přinese si z kuchyně sklenici vody.

But other orders are also possible, depending on emphasis:

• Když je moje dcera žíznivá, sklenici vody si přinese z kuchyně.
• Když je moje dcera žíznivá, z kuchyně si přinese sklenici vody.

These all mean basically the same thing, but the focus shifts a little:

• putting z kuchyně earlier can emphasize from the kitchen
• putting sklenici vody earlier can emphasize a glass of water

The original order is a good neutral version for learners.