Dziś nie mam czasu na naleśniki, więc robię szybką jajecznicę i herbatę z cytryną.

Both dziś and dzisiaj mean today.
Dziś is simply the shorter form, and it is very common in everyday Polish.

So these are both natural:

• Dziś nie mam czasu...
• Dzisiaj nie mam czasu...

The shorter dziś can feel a little more concise, but there is no major difference in meaning here.

Because after negation, Polish very often changes the direct object from the accusative to the genitive.

Without negation:

• Mam czas = I have time

With negation:

• Nie mam czasu = I do not have time

So:

• czas is the basic dictionary form
• czasu is the genitive singular

This is a very important pattern in Polish:

• Mam samochód → Nie mam samochodu
• Mam pieniądze → Nie mam pieniędzy

Czasu is genitive singular of czas.

In this sentence, it appears because of nie mam. As mentioned above, negated mieć usually takes the genitive.

So:

• czas = nominative / basic form
• czasu = genitive singular

Here na means something like for in I don’t have time for pancakes.

After na in this kind of meaning, Polish uses the accusative.

• singular: na naleśnik
• plural: na naleśniki

So na naleśniki is accusative plural.

This structure is very common:

• mam czas na film = I have time for a film
• nie mam czasu na spacer = I don’t have time for a walk

Because Polish often talks about foods like this in the plural when referring to a dish or a typical serving.

So na naleśniki means for pancakes / to make pancakes in a general sense.

If you said na naleśnik, that would suggest for one pancake.

Using the plural sounds natural here because pancakes are usually thought of as a meal made up of more than one.

Because więc means so / therefore, and in Polish it is normally separated by a comma when it links two clauses.

So the sentence is divided like this:

• Dziś nie mam czasu na naleśniki,
• więc robię szybką jajecznicę i herbatę z cytryną.

This is standard Polish punctuation.

Więc means so, therefore, or that’s why.

It introduces the result of the first part of the sentence:

• I don’t have time for pancakes, so...

It often comes near the beginning of the second clause, just like here:

• ..., więc robię...

This is a very common and natural placement.

Yes, robię literally means I do / I make, but in Polish it is often used in a broader way when talking about preparing food.

So robię jajecznicę naturally means:

• I’m making scrambled eggs
• I’m preparing scrambled eggs

Likewise:

• robię obiad = I’m making lunch / preparing lunch
• robię herbatę = I’m making tea

English often uses different verbs like make, cook, or prepare, but Polish very often uses robić.

Because jajecznicę is the direct object of robię, so it is in the accusative singular, and the adjective has to match it.

The noun:

• jajecznica = nominative
• jajecznicę = accusative

The adjective:

• szybka = nominative feminine singular
• szybką = accusative feminine singular

So both words change together:

• szybka jajecznica = quick scrambled eggs as a subject
• robię szybką jajecznicę = I’m making quick scrambled eggs

Because it is a feminine singular noun used as the direct object of the verb robię.

For many feminine nouns ending in -a, the accusative singular changes to -ę:

• jajecznica → jajecznicę
• herbata → herbatę
• kawa → kawę

That is why the sentence has:

• robię szybką jajecznicę i herbatę...

Both food items are direct objects, so both appear in the accusative.

For the same reason as jajecznicę: it is also a direct object after robię.

• herbata = nominative
• herbatę = accusative singular

So:

• Herbata jest gorąca = The tea is hot
• Robię herbatę = I’m making tea

Because Polish, like English, can use one verb with two coordinated objects.

So:

• robię szybką jajecznicę i herbatę z cytryną

means:

• I’m making quick scrambled eggs and tea with lemon

You do not need to repeat robię before herbatę.

If you did repeat it, it would still be understandable, but less natural:

• robię szybką jajecznicę i robię herbatę z cytryną

Here z means with, and when z means with, it takes the instrumental case.

So:

• cytryna = nominative
• cytryną = instrumental singular

That is why you get:

• herbata z cytryną = tea with lemon

This is a very useful pattern:

• kawa z mlekiem = coffee with milk
• kanapka z serem = sandwich with cheese

Be careful: z can also mean from / out of, and then it usually takes a different case. But here it clearly means with.

It describes only jajecznicę.

So the structure is:

• robię [szybką jajecznicę] i [herbatę z cytryną]

If the speaker wanted quick to apply to both items, they would need to phrase it differently.

As written, the meaning is:

• a quick scrambled egg dish
• plus tea with lemon

Yes. Polish word order is more flexible than English word order.

For example, these are also possible:

• Nie mam dziś czasu na naleśniki, więc robię szybką jajecznicę i herbatę z cytryną.
• Dziś robię szybką jajecznicę i herbatę z cytryną, bo nie mam czasu na naleśniki.

But the original version is very natural and neutral.

Putting Dziś first gives a nice today emphasis right away.

Yes. In Polish, jajecznica is a singular noun, even though English usually uses the plural expression scrambled eggs.

So:

• Jajecznica jest gotowa = The scrambled eggs are ready
• Lubię jajecznicę = I like scrambled eggs

This is just a vocabulary difference between the two languages.