Najpierw mieszam ciasto, a potem rozgrzewam piekarnik.

Polish often omits subject pronouns when they are clear from the verb form.

Here, both mieszam and rozgrzewam mean I mix and I preheat / I heat up because the ending -am shows 1st person singular.

So:

• mieszam = I mix
• rozgrzewam = I heat up / I preheat

You could add ja for emphasis:

• Najpierw ja mieszam ciasto, a potem rozgrzewam piekarnik.

But in a normal neutral sentence, ja is usually unnecessary.

• najpierw = first / at first
• potem = then / afterwards

They show the sequence of actions:

• Najpierw mieszam ciasto = First I mix the batter/dough
• a potem rozgrzewam piekarnik = and then I preheat the oven

These are very common time-ordering words in Polish.

These are the 1st person singular present tense forms of the verbs:

• mieszać = to mix
• rozgrzewać = to heat up / to preheat

Conjugation here:

• (ja) mieszam = I mix
• (ja) rozgrzewam = I preheat

For an English speaker, the key thing is that Polish verb endings often tell you who is doing the action, so you do not always need a pronoun.

Both a and i can sometimes translate as and, but they are not always used in the same way.

In this sentence, a potem sounds very natural because a often links one action to the next, especially when moving the story or sequence forward:

• Najpierw... a potem... = First... and then...

Using i potem is possible in some contexts, but a potem is especially common when contrasting or simply sequencing actions smoothly.

So this pattern is very natural:

• Najpierw X, a potem Y.

They are both direct objects, so they are in the accusative case. But in these two nouns, the accusative happens to look the same as the dictionary form.

1. ciasto

• nominative: ciasto
• accusative: ciasto

Since ciasto is a neuter noun, nominative and accusative singular are often identical.

2. piekarnik

• nominative: piekarnik
• accusative: piekarnik

Since piekarnik is a masculine inanimate noun, nominative and accusative singular are also usually identical.

So the case does change grammatically, but the form does not visibly change here.

Ciasto is a tricky word because it can mean different things depending on context:

• cake
• cake batter
• dough
• sometimes more generally a baked mixture

In the sentence Najpierw mieszam ciasto, the most natural meaning is usually:

• I mix the batter or
• I mix the dough

The exact English translation depends on what is being made. Polish uses ciasto more broadly than English uses cake.

Yes, in context that is a very natural translation.

Literally, rozgrzewam means something like:

• I warm up
• I heat up

So:

• rozgrzewam piekarnik = I heat up the oven
• in cooking English, that is usually I preheat the oven

So preheat the oven is often the best natural English equivalent, even if the Polish verb is more literally heat up.

Yes, it is in the present tense.

• mieszam = I mix / I am mixing
• rozgrzewam = I preheat / I am preheating

Polish present tense can be used in several ways, including:

• describing what someone is doing now
• describing a routine
• narrating steps in a process

So this sentence could mean:

• Right now, first I mix the batter, then I preheat the oven
• or When I do this, first I mix the batter, then I preheat the oven

English often chooses the most natural translation based on context.

Yes, Polish word order is fairly flexible, although some orders sound more natural than others.

The original sentence:

• Najpierw mieszam ciasto, a potem rozgrzewam piekarnik.

is very natural and neutral.

You could also say:

• Ciasto najpierw mieszam, a potem rozgrzewam piekarnik.
• Najpierw ciasto mieszam, a potem rozgrzewam piekarnik.

But these alternatives can sound more marked, with extra emphasis on ciasto or on the order of actions.

For learners, the original version is the best model:

• Najpierw + verb + object, a potem + verb + object

The verbs mieszać and rozgrzewać here are imperfective.

That makes sense because the sentence describes the process or sequence of actions, not just their completion.

• mieszać = to be mixing / to mix
• rozgrzewać = to be heating up / to preheat

In Polish, imperfective verbs are commonly used for:

• ongoing actions
• repeated actions
• general procedures
• step-by-step descriptions

That fits a cooking context very well.

A simple approximate pronunciation for an English speaker is:

NAI-pyerv MYESZ-am CHAHS-to, a PO-tem roz-GZHE-vam pyek-AR-nik

A few helpful notes:

• najpierw: the j sounds like English y
• mieszam: mie is roughly mye
• ciasto: cia sounds a bit like cha
• rozgrzewam: rz sounds like the s in measure
• piekarnik: pie sounds roughly like pye

Polish pronunciation is regular, but consonant clusters can take some practice.

Because a is a coordinating conjunction, and in Polish it is normally preceded by a comma when it links two clauses.

So:

• Najpierw mieszam ciasto, a potem rozgrzewam piekarnik.

This is standard Polish punctuation.

In English, we also often use a comma in similar sentences:

• First I mix the batter, and then I preheat the oven.

So the comma here is completely normal.