Learn Hardcore Polish: Ona nie lubi plotek, więc rzadziej rozmawia z nerwową ciocią. - She does not like gossip, so she talks less often with the nervous aunt.

The base noun is plotka (a piece of gossip).
Its normal accusative plural is plotki: Ona lubi plotki – She likes gossip.
But in Polish, a direct object in a negated sentence is very often put into the genitive case, not accusative.
So when you negate lubić, plotki (accusative plural) usually becomes plotek (genitive plural): Ona nie lubi plotek. Both forms can sometimes be heard, but genitive after negation is the standard/most natural here.

So what case is plotek, and how is that form built from plotka?

Plotek is genitive plural.
The pattern is:

nominative singular: plotka
nominative plural: plotki
genitive plural: plotek

Many feminine nouns in -ka form the genitive plural by dropping -a and taking -ek (e.g. książka → książek, łatka → łatek).
You usually just have to learn the genitive plural form with each noun, because it’s often irregular from an English perspective.

What exactly does więc mean, and how is it different from bo or dlatego?

Więc means so / therefore, introducing a result or consequence: she doesn’t like gossip, so she talks less often with her aunt.
Bo means because and introduces the reason: Ona rzadziej rozmawia z ciocią, bo nie lubi plotek – She talks less often with her aunt because she doesn’t like gossip.
Dlatego also means that’s why / therefore, but it’s usually followed by a clause with normal word order: Nie lubi plotek, dlatego rzadziej rozmawia z ciocią.
So: bo = because, więc / dlatego = so / therefore, just with slightly different typical positions in the sentence.

What does rzadziej mean, and what is the basic form?

Rzadziej means less often / more rarely.
The basic adverb is rzadko – rarely, not often.
Rzadziej is its comparative form:

rzadko – rarely
rzadziej – more rarely / less often
najrzadziej – most rarely / least often

Why do we use rzadziej and not mniej here?

Mniej means less in general (less of something: quantity, degree, etc.).
Rzadziej specifically modifies frequency – how often something happens.
So:

mniej rozmawia – she talks less (in general / fewer minutes / fewer words)
rzadziej rozmawia – she talks less often / more rarely

In the sentence, the idea is about frequency, so rzadziej is the natural choice.

Why is it z nerwową ciocią and not just z nerwowa ciocia?

The preposition z (with) almost always takes the instrumental case.
The base forms are nerwowa ciocia (nominative singular, nervous aunt).
In the instrumental singular, feminine nouns typically end in -ą, and adjectives that agree with them also end in -ą:

nominative: nerwowa ciocia
instrumental: nerwową ciocią

So z nerwową ciocią literally means with (the) nervous aunt in the instrumental case.

What is the instrumental case doing here exactly?

In this sentence, the instrumental is required by the preposition z (with).
Many Polish prepositions always combine with a specific case; z meaning with (someone) normally uses instrumental.
So to say with the aunt, you must put ciocia into the instrumental: ciocią.
Other common prepositions that trigger instrumental include nad, pod, przed, między in certain meanings.

Why does nerwową end with -ą?

Nerwową is an adjective modifying ciocią, so it must agree in gender, number, and case with the noun.
Ciocią is feminine singular instrumental, so the adjective also takes the feminine singular instrumental ending -ą: nerwową ciocią.
In nominative you’d have nerwowa ciocia, but with z you switch to instrumental: z nerwową ciocią.

Why is it rozmawia z and not mówi z or something else?

Rozmawiać z kimś means to talk / have a conversation with someone – it emphasizes a two‑way exchange.
Mówić is more general: to speak, to say, to talk, and is often used with do (to) rather than z (with): mówić do kogoś – to speak to someone.
You can also hear mówić z kimś, but rozmawiać z kimś is the most natural phrase for having conversations with someone.
So here, rozmawia nicely matches the idea that she has conversations with her aunt.

What’s the aspect and tense of rozmawia, and how would you say it in the past?

Rozmawia is present tense, imperfective aspect of rozmawiać.
Imperfective here expresses a habitual action: she (generally) talks less often with her aunt.
In the past, you’d say:

Ona rzadziej rozmawiała z nerwową ciocią. – She talked less often with her nervous aunt.

For a single, completed conversation, you’d more likely choose the perfective verb porozmawiać:
Ona porozmawiała z ciocią. – She had a talk with her aunt (once, completed).

Could you also drop ona and just say Nie lubi plotek, więc rzadziej rozmawia z nerwową ciocią?

Yes, and in natural conversation that’s actually more typical.
Polish normally omits subject pronouns when the verb ending already shows the person and number.
So Nie lubi plotek, więc rzadziej rozmawia z nerwową ciocią is fully correct and sounds a bit more natural.
Including ona adds a bit of emphasis or contrast: She (as opposed to someone else) doesn’t like gossip, so she talks less often with her aunt.

Why is there no word for a/the in this sentence?

Polish simply does not have articles like a, an, the.
Whether it feels like a or the in English depends on context and word order, not on a special word.
So nerwową ciocią could be translated as a nervous aunt or the nervous aunt, depending on what the wider context implies.
Learners usually have to infer definiteness from context, intonation, and what has been mentioned before.

Can the word order be changed, like Ona z nerwową ciocią rzadziej rozmawia?

Yes, Polish word order is relatively flexible, and Ona z nerwową ciocią rzadziej rozmawia is grammatically correct.
The neutral, most common order in this style is still Ona nie lubi plotek, więc rzadziej rozmawia z nerwową ciocią.
When you move parts around, you often change the focus or emphasis rather than the basic meaning.
For example, putting z nerwową ciocią earlier can highlight with whom she talks less often.

How do you pronounce rzadziej and ciocią?

rzadziej:
- rz sounds like the s in measure or vision;
- stress is on the first syllable: RZAD-jey (['ʐad.ʑɛj]).
ciocią:
- cio is like chyo, with a soft ch;
- ą is a nasal vowel, roughly like on in French bon, but at the very end it often sounds close to -om or -on;
- stress on the first syllable: CHYO-chon ([ˈt͡ɕɔ.t͡ɕɔ̃]).

Remember that in Polish, stress almost always falls on the second‑to‑last syllable, which helps with words like these.