W tej kawiarni zamówiłam sernik, a mój chłopak pączka, bo nie miał ochoty na lody.

Because zamówiłam is the past tense, first person singular, feminine form of zamówić (to order).

So the speaker is a woman.

• zamówiłam = I ordered (said by a woman)
• zamówiłem = I ordered (said by a man)

Polish past tense usually shows the gender of the speaker in the singular.

W tej kawiarni means in this café.

It uses the preposition w (in), which here requires the locative case.

That is why the words change:

• ta kawiarnia = this café / this coffee shop
• w tej kawiarni = in this café

So:

• ta → tej
• kawiarnia → kawiarni

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

Because sernik is a masculine inanimate noun, and in Polish, the accusative singular of masculine inanimate nouns is usually the same as the nominative singular.

So:

• sernik = cheesecake (nominative)
• zamówiłam sernik = I ordered cheesecake (accusative, but same form)

That is why you do not see a change here.

This is a very common question.

Pączek means doughnut, but after the implied verb zamówił (ordered), we get pączka.

So the full version would be:

• mój chłopak zamówił pączka

Many masculine nouns referring to foods are often treated like masculine animate in the accusative, so their accusative looks like the genitive:

• pączek → pączka

This can feel surprising, because a doughnut is not literally animate. But this pattern is normal in Polish with some food words.

Because Polish often omits a repeated verb when it is easy to understand from context.

The full sentence would be:

• W tej kawiarni zamówiłam sernik, a mój chłopak zamówił pączka...

But since zamówił is obvious, it is left out:

• W tej kawiarni zamówiłam sernik, a mój chłopak pączka...

This kind of omission is very natural and common in Polish.

Here a is better translated as something like and, while, or whereas, depending on context.

It connects two contrasting pieces of information:

• I ordered cheesecake
• my boyfriend ordered a doughnut

So a often signals a mild contrast or comparison between two parts of the sentence.

If you used i, it would sound more like simple addition:

• X and Y

But a is very natural when comparing what different people did.

Yes, in normal modern Polish, mój chłopak usually means my boyfriend.

Word for word, chłopak can mean boy, guy, or boyfriend depending on context, but with mój in a sentence like this, the natural meaning is my boyfriend.

The basic expression is:

• mieć ochotę na coś = to feel like something / to be in the mood for something

In the affirmative:

• Miał ochotę na lody = He felt like having ice cream

But with negation, Polish often uses the genitive instead of the accusative after mieć:

• Nie miał ochoty = He didn’t feel like...

So:

• ochota = nominative
• ochotę = accusative
• ochoty = genitive

In this sentence, the negation nie miał leads to ochoty.

Because in Polish, lody (ice cream) is normally used in the plural.

So even though English often uses singular ice cream, Polish says:

• lody = ice cream

Examples:

• Lubię lody = I like ice cream
• Nie miał ochoty na lody = He didn’t feel like ice cream

This is just how the noun is normally used in Polish.

Ochota na coś means a desire for something, a craving for something, or feeling like something.

So:

• mieć ochotę na lody = to feel like ice cream
• nie mieć ochoty na lody = not to feel like ice cream

It is a very common everyday expression.

Polish word order is more flexible than English word order.

Starting with W tej kawiarni puts the setting first:

• In this café, I ordered cheesecake...

This can sound natural when the speaker wants to establish the place before saying what happened there.

You could also say:

• Zamówiłam sernik w tej kawiarni...

But the original version gives a slightly different emphasis by foregrounding the location.

Zamówić is perfective.

It focuses on a completed action:

• zamówić = to order (successfully, as a completed act)

So zamówiłam sernik means I ordered cheesecake as a finished event.

The imperfective partner is zamawiać, which would be used for repeated actions, habits, or ongoing situations.

For example:

• Zawsze zamawiałam sernik = I always used to order cheesecake

But here we are talking about one completed event, so zamówiłam is the natural choice.

Yes. A fully expanded version would be:

W tej kawiarni zamówiłam sernik, a mój chłopak zamówił pączka, bo nie miał ochoty na lody.

This makes the omitted verb explicit.

You could translate it roughly as:

In this café, I ordered cheesecake, and my boyfriend ordered a doughnut because he didn’t feel like ice cream.

The shorter original sentence is just a more natural, economical way of saying the same thing.