W tym zdaniu najpierw jest rzeczownik, a dopiero potem czasownik.

Because the preposition w meaning in requires the locative case when it refers to location.

• to zdanie = this sentence in the nominative
• w tym zdaniu = in this sentence in the locative

So both words change:

• to → tym
• zdanie → zdaniu

This is a very common pattern in Polish after w when it means in.

It is the locative singular.

The base noun is:

• zdanie = sentence

Its locative singular form is:

• zdaniu

And the demonstrative adjective agrees with it:

• tym = in/at this

So:

• w tym zdaniu = in this sentence

Because zdanie is a neuter noun, and in the locative singular many neuter nouns ending in -e change to -u.

For example:

• zdanie → w zdaniu
• pytanie → w pytaniu

This is just part of Polish case inflection. English learners often need to get used to the fact that noun endings change depending on grammatical role.

Najpierw means first or first of all.

In this sentence, it tells us the order of elements:

• najpierw jest rzeczownik = first there is a noun

It is an adverb, so it describes sequence, not a noun or adjective.

Jest is the 3rd person singular of być (to be).

Here it means is or there is, depending on how naturally you translate it into English.

So:

• najpierw jest rzeczownik = literally first is a noun
• more natural English: first there is a noun or the noun comes first

Polish often uses jest in places where English might prefer a different structure.

They are both in the nominative singular:

• rzeczownik = noun
• czasownik = verb

After jest, Polish often uses the nominative when identifying or naming something in a simple statement like this.

So:

• jest rzeczownik = there is a noun
• potem czasownik = then a verb

The sentence is talking about what appears in the sentence structure, not showing possession or direction, so the basic form makes sense here.

This is an important nuance.

• a potem = and then / and afterward
• a dopiero potem = and only then / and not until afterward

The word dopiero adds emphasis. It suggests that the second thing happens later than the first, and that this ordering matters.

So:

• najpierw jest rzeczownik, a dopiero potem czasownik = first there is a noun, and only then a verb

This sounds more contrastive and deliberate than simply and then.

Here a is a conjunction linking two contrasting or balanced parts of the sentence.

In many cases, a can be translated as:

• and
• while
• but

depending on context.

In this sentence, it connects two stages in sequence with a slight contrast:

• najpierw ...
• a dopiero potem ...

So it works a bit like and then / whereas then / and only afterward.

It is not exactly the same as i.

• i = plain and
• a = a looser connection, often with contrast or comparison

Yes, that is close to the literal structure, but it is not natural English.

A more natural translation would be:

• In this sentence, the noun comes first, and only then the verb.
• In this sentence, there is a noun first, and only then a verb.

The Polish sentence is grammatically normal in Polish, but English usually wants either:

• the noun comes first or
• there is a noun first

rather than first is a noun.

Because Polish has no articles like English a/an/the.

So:

• rzeczownik can mean a noun or the noun
• czasownik can mean a verb or the verb

The exact meaning depends on context.

In this sentence, English would usually choose:

• a noun
• a verb

or, if talking about sentence structure more generally:

• the noun
• the verb

Polish leaves that distinction unstated unless something else makes it clear.

Not completely. Polish word order is more flexible than English, but different orders change emphasis.

The given sentence:

• W tym zdaniu najpierw jest rzeczownik, a dopiero potem czasownik.

is very natural and emphasizes the sequence clearly.

You could rearrange parts, for example:

• Najpierw w tym zdaniu jest rzeczownik, a dopiero potem czasownik.

This is still understandable, but the emphasis shifts slightly.

Even though Polish allows flexibility, the original order sounds smooth and idiomatic.

Polish often omits repeated words when they are easy to understand from context.

The full version could be:

• W tym zdaniu najpierw jest rzeczownik, a dopiero potem jest czasownik.

But repeating jest is not necessary, so Polish commonly leaves it out:

• ... a dopiero potem czasownik.

English does something similar sometimes:

• First a noun, then a verb.

So this omission is very natural.

They are similar, and both can often mean later or then, but they are not always identical in tone or use.

• potem often means then / afterward
• później often means later

In this sentence, potem fits the idea of sequence very naturally:

• najpierw ... potem ... = first ... then ...

That pair is extremely common in Polish.

The natural emphasis would usually fall on the sequence words and the contrasted elements:

• W tym zdaniu NAJPIERW jest RZECZOWNIK, a dopiero POTEM CZASOWNIK.

This highlights the key idea: the order is noun first, verb later.

The phrase a dopiero potem especially tends to carry strong contrastive emphasis.

Yes, it is a very natural explanatory sentence, especially in grammar discussion or language teaching.

It uses several common Polish patterns:

• w tym zdaniu = in this sentence
• najpierw ... potem ... = first ... then ...
• a dopiero potem = and only then
• omitted repeated jest

So besides its meaning, it is also a useful model for talking about order and structure in Polish.