Po kołysance dziecko śpi spokojnie.

Here po means after.

So Po kołysance dziecko śpi spokojnie means something like:

• After the lullaby, the child sleeps peacefully.

A very important thing to remember is that po usually requires the locative case in this kind of time expression.

Because the preposition po takes the locative case here.

The dictionary form is:

• kołysanka = lullaby

But after po, it changes to:

• po kołysance = after the lullaby

This is a normal case change in Polish.
For feminine nouns ending in -a, the locative singular often ends in -e or -ce, depending on the word.

So:

• kołysanka → kołysance

Kołysanka means lullaby.

It comes from the idea of rocking a child to sleep. In this sentence, it refers to the song or soothing action that helps the child fall asleep.

So po kołysance most naturally means:

• after the lullaby
• sometimes more loosely, after being sung a lullaby

Polish does not have articles like a or the.

So dziecko can mean:

• a child
• the child

Which one sounds right depends on context.

In this sentence, English would often use the child if both speaker and listener know which child is meant, but Polish simply says dziecko.

Because spokojnie is an adverb, and it describes how the child sleeps.

• spokojny = calm / peaceful as an adjective
• spokojnie = calmly / peacefully as an adverb

Since it modifies the verb śpi (sleeps), Polish uses the adverb:

• dziecko śpi spokojnie = the child sleeps peacefully

If you used spokojne, that would describe the child itself, not the manner of sleeping:

• dziecko jest spokojne = the child is calm

Śpi is the 3rd person singular present tense of the verb spać (to sleep).

So it means:

• he sleeps
• she sleeps
• it sleeps

Since dziecko is grammatically singular, you use śpi.

Examples:

• Ja śpię = I sleep / I am sleeping
• Ty śpisz = you sleep / are sleeping
• Dziecko śpi = the child sleeps / is sleeping

Like many Polish present-tense verbs, it can correspond to either simple present or present progressive in English, depending on context.

Because dziecko is grammatically neuter in Polish.

That means adjectives and verbs agree with it as a neuter singular noun where relevant. This is about grammar, not about how people think of an actual child.

For example:

• małe dziecko = a small child
• dziecko śpi = the child is sleeping

In English, you would usually say the child rather than it, but in Polish the grammatical gender is still neuter.

Polish word order is fairly flexible, though some orders sound more natural in certain contexts.

The given sentence:

• Po kołysance dziecko śpi spokojnie.

is natural and neutral.

You could also say:

• Dziecko po kołysance śpi spokojnie.
• Dziecko śpi spokojnie po kołysance.

These are all understandable, but they may shift emphasis slightly:

• starting with Po kołysance highlights the time sequence: after the lullaby
• starting with Dziecko highlights the child

So the original sentence is a very natural way to present the situation.

Usually it means after the lullaby, without specifying exactly how much time passed.

In many contexts, it suggests a natural sequence:

• first the lullaby
• then the child sleeps peacefully

It often feels fairly immediate, but grammatically it does not require immediately after. If you wanted to stress immediacy, Polish would need extra wording.

A few key sounds may be unfamiliar to English speakers:

• ł sounds like English w
• ś is a soft sh-like sound
• ć / ci, ń / ni, ś / si are often softer than their nearest English equivalents

Rough pronunciation guide:

• kołysance ≈ ko-wi-SAN-tseh
• śpi ≈ shpyi or soft-shpi

More specifically:

• ko-ły-san-ce
• ł = w
• ce here sounds like tseh
• śpi begins with a soft ś followed by pi

The śp cluster can be tricky at first, but it is common in Polish.

Usually kołysanka specifically means lullaby, not just rocking.

So the most natural translation is:

• After the lullaby, the child sleeps peacefully.

If you wanted to say after rocking more literally, Polish would normally use a different wording based on a verb like kołysać (to rock).

So in this sentence, kołysanka is best understood as lullaby.

A few useful things appear here at once:

1. Preposition + case

   • po
     • locative
   • po kołysance

2. No articles

   • dziecko can mean a child or the child

3. Present tense verb

   • śpi from spać

4. Adverb formation

   • spokojnie describes how the sleeping happens

So this short sentence is a good example of how Polish packs meaning into:

• case endings
• verb forms
• adverbs rather than using extra function words like English often does.