Ta lalka ma czerwony sweter, a ten miś śpi już na łóżku.

Because Polish demonstratives must agree with the noun’s grammatical gender.

• ta = feminine singular
• ten = masculine singular
• to = neuter singular

Here:

• lalka (doll) is feminine, so: ta lalka
• miś (teddy bear / little bear) is masculine, so: ten miś

This is similar to how adjectives also have to match the noun in Polish.

The adjective czerwony has to agree with sweter in gender, number, and case.

• sweter is masculine singular
• it is in the nominative here
• so the adjective also takes the masculine nominative singular form: czerwony

Compare:

• czerwony sweter = masculine
• czerwona lalka = feminine
• czerwone łóżko = neuter

So czerwony is used because it matches sweter.

Ma means has.

It is the 3rd person singular form of the verb mieć = to have.

So:

• ja mam = I have
• ty masz = you have
• on / ona / ono ma = he / she / it has

In this sentence, Ta lalka ma czerwony sweter literally means This doll has a red sweater.

Miś is a diminutive, affectionate word. It usually means:

• teddy bear
• or little bear / cute bear

Niedźwiedź is the ordinary word for bear.

In a children’s context, toy context, or cute context, miś is very common. In this sentence, it most likely means teddy bear.

Już usually means already.

So ten miś śpi już na łóżku means something like:

• that teddy bear is already sleeping on the bed

In Polish, już is quite flexible in position, but its placement can slightly affect emphasis.

For example:

• Miś już śpi = The teddy bear is already sleeping.
• Miś śpi już na łóżku = The teddy bear is already sleeping on the bed.

In your sentence, już naturally suggests that the bear is now in that state or location.

Because na can take different cases depending on meaning.

When na means on in the sense of location, it takes the locative case.

• na łóżku = on the bed

When na expresses movement toward something, it often takes the accusative.

• położyć na łóżko = to put onto the bed
• iść na łóżko is not natural in this context, but grammatically it would show movement toward the bed

So here:

• the teddy bear is already sleeping in a location
• therefore Polish uses the locative: na łóżku

Because after na for location, the noun must be in the locative case.

The dictionary form is:

• łóżko = bed

But in the locative singular, it becomes:

• na łóżku = on the bed

This is a normal case ending change in Polish. Many neuter nouns in -o change to -u in the locative singular.

A often connects two ideas with a slight contrast or topic shift, while i usually just means and in a straightforward way.

So:

• X..., a Y... often feels like X..., while Y... or X..., and meanwhile Y...
• X i Y is more simply X and Y

In this sentence:

• Ta lalka ma czerwony sweter, a ten miś śpi już na łóżku.

The speaker is talking about one toy, then shifting to another toy. A works very naturally for that kind of contrast or change of focus.

Because Polish has no articles.

English distinguishes:

• a doll
• the doll

Polish usually does not mark that directly with an article. Instead, context or words like demonstratives help show the meaning.

So:

• lalka can mean a doll or the doll
• ta lalka means this doll
• ten miś means this/that teddy bear, depending on context

Polish relies much more on context than English does for definiteness.

Śpi means is sleeping / sleeps.

It is the 3rd person singular form of spać = to sleep.

Basic forms:

• ja śpię = I sleep / am sleeping
• ty śpisz = you sleep / are sleeping
• on / ona / ono śpi = he / she / it sleeps / is sleeping

In Polish, the present tense can often translate into either simple present or present continuous in English, depending on context.

So miś śpi can mean:

• the teddy bear sleeps
• the teddy bear is sleeping

Here, is sleeping is the natural English translation.

Not completely. Polish word order is more flexible than English word order because case endings show grammatical relationships.

The given sentence is natural:

• Ta lalka ma czerwony sweter, a ten miś śpi już na łóżku.

But other orders are also possible, with different emphasis. For example:

• Już ten miś śpi na łóżku emphasizes already
• Na łóżku już śpi ten miś emphasizes the location

Even though many word orders are possible, the original version sounds neutral and natural for a simple description.

A few sounds here are especially important for English speakers:

• ś is a soft sh-like sound, made further forward in the mouth than English sh
• miś sounds roughly like meesh, but with a softer ś
• śpi sounds roughly like shpee, again with a soft ś
• ł is pronounced like English w
• ó is pronounced like u in boot
• ż sounds like the s in measure
• łóżku sounds roughly like woozh-koo

So:

• miś ≈ meesh
• śpi ≈ shpee
• łóżku ≈ woozh-koo

These are only approximations, but they are helpful starting points.

Yes. In many contexts, ten is best translated as this, but depending on situation and English style, it can sometimes come across as that.

Polish has:

• ten / ta / to = this / that in many everyday contexts
• more explicitly distant forms also exist, but they are much less common in ordinary speech

So in a simple sentence like this, ten miś usually means this teddy bear, but English translation may vary depending on what sounds most natural in context.