Když je venku zima, naše děti si hrají doma.

Když means when here. It introduces a subordinate clause: Když je venku zima = When it is cold outside.

It is a very common way to talk about situations that happen regularly, not just one single moment. In this sentence, it suggests a general pattern:

• When it’s cold outside, our children play at home.

You will also often see když in sentences meaning when in the sense of whenever.

Because Když je venku zima is a subordinate clause, and in Czech subordinate clauses are normally separated by a comma.

So the structure is:

• Když je venku zima, = subordinate clause
• naše děti si hrají doma. = main clause

This comma is required in standard Czech.

Literally, it is something like:

• it is outside cold

A more natural English translation is:

• it is cold outside

Czech often uses je + noun/adverbial expression to talk about weather and conditions.

Here:

• je = is
• venku = outside
• zima = cold

So the whole phrase means that the weather outside is cold.

Yes. Zima can mean both:

• winter
• cold

In this sentence, it clearly means cold, not the season itself.

Czech often uses zima in expressions like:

• Je zima. = It is cold.
• Je mi zima. = I am cold.

So even though English uses an adjective (cold), Czech often uses the noun zima in this kind of expression.

Because děti is the plural of dítě, which is a neuter noun in the singular. In the nominative plural, the possessive adjective agrees with it as naše.

So:

• naše děti = our children

For English speakers, this is easy to overthink because children are people, but Czech agreement follows the grammatical gender and declension pattern of the noun, not natural gender in the English sense.

This is one of the most important parts of the sentence.

The Czech verb for to play in the sense of children playing is usually:

• hrát si

So si is not optional here in normal usage. It is part of the expression.

Compare:

• děti si hrají = the children are playing
• hrát without si often means to play something, especially a game, sport, instrument, or role:
  • hrát fotbal = to play football
  • hrát na klavír = to play the piano
  • hrát roli = to play a role

So hrát si specifically means to play in the general sense of amusing oneself, especially for children.

Not if you mean our children play at home in the general child-play sense.

Without si, hrají usually sounds incomplete or suggests that they are playing something specific:

• hrají fotbal = they are playing football
• hrají hru = they are playing a game

If you simply want to say children are playing, the normal form is:

• naše děti si hrají doma

Both are possible, but si is a clitic, so it tends to go in the second position of its clause.

That is why naše děti si hrají doma sounds very natural.

You may also hear:

• Naše děti hrají si doma

but that is not the normal neutral word order. It sounds awkward in standard Czech.

The usual neutral order is:

• naše děti si hrají doma

So for learners, it is best to remember that short unstressed words like si usually come very early in the clause.

Doma means at home.

That is the natural word to use here:

• naše děti si hrají doma = our children play at home

By contrast:

• v domě means in the house/building

So the difference is roughly:

• doma = at home, in the home environment
• v domě = inside the building

In most everyday situations where English says at home, Czech uses doma.

Yes. That is very normal in Czech.

• venku = outside
• doma = at home

They function as adverbs, so you do not need a preposition before them.

Examples:

• Je venku teplo. = It is warm outside.
• Jsem doma. = I am at home.

This is different from English, where you often need outside or at home as fixed expressions.

Because Czech uses an impersonal singular construction for weather and general conditions.

So:

• Je zima. = It is cold.
• Je teplo. = It is warm.

The verb is third person singular je = is, similar to English it is, even though Czech does not usually need an explicit subject like English it.

Sometimes když can overlap a little with if in everyday Czech, especially in conversational language, but in this sentence the most natural meaning is when/whenever.

So the idea is:

• Whenever it is cold outside, our children play at home.

If you wanted a clearer conditional if, Czech often uses jestli or pokud, depending on context.

It most naturally describes a general habit.

That comes from the combination of:

• když = when/whenever
• present tense je, hrají

So it means something like:

• Whenever it is cold outside, our children play at home.

It could refer to a current situation in the right context, but the default reading is habitual.

A rough English-friendly guide would be:

• děti ≈ dye-ti
• si = si
• hrají ≈ hra-yee

A few useful notes:

• dě is not a plain de; it is a softer sound, roughly like dye
• h in Czech is pronounced clearly, not silent
• ají in hrají has two syllables at the end: a-jí

A rough full pronunciation of the sentence could be written as:

• Kdysh ye venku zima, nashe dye-ti si hra-yee doma.

That is only approximate, but it can help at the beginning.