Ta bajka jest spokojna, więc po niej maluch szybciej zasypia.

Because bajka is a feminine singular noun in Polish. The demonstrative ta means this and must agree with the noun’s gender, number, and case.

• ten = this (masculine)
• ta = this (feminine)
• to = this (neuter)

So:

• ta bajka = this story / this fairy tale

The adjective has to agree with bajka.

Since bajka is feminine singular, the adjective also takes the feminine singular form:

• spokojny = masculine
• spokojna = feminine
• spokojne = neuter

So:

• Ta bajka jest spokojna = This story is calm/gentle/soothing

Literally, spokojna means calm, peaceful, or quiet. In this sentence, it probably means the story has a gentle, soothing effect rather than being exciting or intense.

So in natural English, it might suggest:

• This story is calm
• This story is gentle
• This story is soothing

The best choice depends on context.

Jest is the 3rd person singular form of być (to be), so it means is.

• Ta bajka jest spokojna = This story is calm

In standard Polish, when you say that something is something, you normally use jest. Unlike in Russian, for example, Polish usually does not drop the present-tense to be in ordinary sentences like this.

So Ta bajka spokojna would sound incomplete or nonstandard in normal speech.

Więc means so, therefore, or thus. It introduces a result.

• Ta bajka jest spokojna, więc po niej maluch szybciej zasypia.
• This story is soothing, so the little one falls asleep faster after it.

It is not the same as bo.

• bo = because (gives the reason)
• więc = so / therefore (gives the result)

Compare:

• Maluch szybciej zasypia, bo bajka jest spokojna.
  = The little one falls asleep faster because the story is calm.

• Bajka jest spokojna, więc maluch szybciej zasypia.
  = The story is calm, so the little one falls asleep faster.

Because the preposition po requires a specific case here, and the pronoun has to match bajka.

Bajka is feminine, so the pronoun it/her comes from ona. After po, the form becomes niej.

So:

• po niej = after it / after her

In this sentence, po niej means after that story.

This is a very common pattern:

• po obiedzie = after lunch
• po filmie = after the film
• po niej = after it (feminine noun)

Here, niej is in the locative case after the preposition po.

For personal and demonstrative-style reference, English speakers often need to get used to the fact that Polish pronouns change form depending on case.

The base pronoun is:

• ona = she / it (for feminine nouns)

But after different prepositions or in different grammatical roles, it changes:

• ją / nią
• jej
• niej

In po niej, the form niej is required by po in this meaning of after.

Maluch literally means something like little one. In this context, it usually refers to a small child, toddler, or young kid.

It is a warm, natural word, often used by parents or in child-related contexts. It is a bit more affectionate and specific than just dziecko.

Rough comparison:

• dziecko = child
• maluch = little one / toddler / little kid

So maluch gives a softer, more intimate tone.

Szybciej is the comparative adverb of szybko (quickly).

• szybko = quickly
• szybciej = more quickly / faster

So:

• maluch szybciej zasypia = the little one falls asleep faster

Polish often uses the comparative without explicitly saying than. The comparison is understood from context: faster than usual, faster than after another story, and so on.

Because zasypiać means to fall asleep, while spać / śpi means to sleep / is sleeping.

That difference is important:

• śpi = is asleep / is sleeping
• zasypia = falls asleep / is falling asleep

So the sentence is about the process of going to sleep, not the state of already being asleep.

Zasypia is imperfective, and zaśnie is the future perfective form.

Here, zasypia works well because the sentence describes a general tendency or habitual result:

• This story is soothing, so the little one falls asleep faster.

That sounds like something that happens regularly.

If you said zaśnie, it would usually point more to one future occasion:

• Po niej maluch szybciej zaśnie = After it, the little one will fall asleep faster

So:

• zasypia = habitually / generally falls asleep
• zaśnie = will fall asleep (in a specific future situation)

No, Polish word order is fairly flexible. The sentence given is natural, but other orders are also possible.

For example:

• Po niej maluch szybciej zasypia.
• Maluch po niej szybciej zasypia.
• Maluch szybciej zasypia po niej.

These all mean roughly the same thing, but the emphasis shifts slightly.

• Po niej at the start highlights after it
• maluch earlier can highlight the child
• szybciej earlier can highlight faster

The original version sounds very natural and well balanced.

Because Polish does not have articles like English a and the.

So bajka can mean:

• a story
• the story
• just story

The exact meaning depends on context.

In this sentence, ta bajka already makes it specific, because ta means this, so there is no need for an article:

• ta bajka = this story

Likewise, maluch can mean the little one or a little child, depending on context.