Nie zawsze ważne jest, ile kto ma lat; w dobrym związku ważniejsze są prawda, spokój i rozmowa.

Because the grammatical subject of the first clause is not a noun like wiek or związek. It is the whole clause ile kto ma lat.

In Polish, when the subject is a whole clause, the predicate adjective is usually put in the neuter singular form. So:

• Ważne jest, że... = It is important that...
• Dziwne było, że... = It was strange that...

So in your sentence:

• Nie zawsze ważne jest, ile kto ma lat

the ważne is neuter singular because it refers to the entire idea how old someone is.

Both are possible, but the given order sounds natural and slightly more polished.

Polish word order is more flexible than English, and it is often used to control emphasis. Here:

• Nie zawsze ważne jest, ile kto ma lat

puts ważne early, so the sentence highlights the idea of importance.

You could also say:

• Nie zawsze jest ważne, ile kto ma lat
• To, ile kto ma lat, nie zawsze jest ważne

All of these are grammatical. The original version is just a very natural written style.

Literally, it means how many years someone has, which is the normal Polish way to express age.

So:

• ile kto ma lat = how old someone is

This is an indirect-question structure:

• ile = how many
• kto = who / a person / whoever is being talked about
• ma lat = has years

It does not sound word-for-word like English, but it is a normal Polish way of expressing the idea.

Here kto has a more general meaning: who / any given person / whoever the person is. It works well in general statements.

So:

• ile kto ma lat means something like how old a person is or how old someone may be

By contrast, ktoś means someone, usually an unspecified individual person. That would sound more like you are talking about one unknown person in particular.

So the sentence uses kto because it is making a general statement about people, not about one unidentified individual.

Age in Polish is expressed with mieć + number + year-word, and the form of the year-word changes depending on the number.

Common patterns are:

• 1 rok
• 2, 3, 4 lata
• 5+ lat
• ile lat = how many years / how old

So in this sentence:

• ile kto ma lat

the word lat is correct because ile requires the genitive plural here.

Also, roków is generally not the normal everyday form in age expressions. For age, Polish overwhelmingly uses rok / lata / lat.

Examples:

• Ma 1 rok
• Ma 3 lata
• Ma 20 lat
• Ile masz lat?

Because the subjects are different.

In the first clause:

• ważne jest, ile kto ma lat

the subject is the whole clause ile kto ma lat, and that is treated as singular.

In the second clause:

• ważniejsze są prawda, spokój i rozmowa

the subject is a list of three nouns:

• prawda
• spokój
• rozmowa

Together, they make a plural subject, so Polish uses są.

So:

• clause subject → jest
• multiple nouns → są

Ważniejsze is the comparative form of ważne / ważny, meaning more important.

The sentence is making an implied comparison:

• a person’s age is not always important;
• in a good relationship, truth, peace/calm, and conversation are more important.

Polish often leaves the comparison target unstated if it is obvious from context. So here ważniejsze really means:

• more important than age

You do not need to add niż wiek or niż to, ile kto ma lat, because the previous clause already makes that clear.

Because they are in the nominative case, functioning as the subject of są ważniejsze.

So:

• prawda = nominative singular
• spokój = nominative singular
• rozmowa = nominative singular

A common confusion for learners is that after jest Polish sometimes uses the instrumental, for example:

• Jan jest lekarzem = Jan is a doctor

But that happens when the predicate is a noun. Here the predicate is an adjective:

• ważniejsze są...

So the nouns remain nominative because they are the subject.

It is the locative case, because the preposition w meaning in normally takes the locative.

Breakdown:

• w = in
• dobrym = locative singular of dobry
• związku = locative singular of związek

So:

• w dobrym związku = in a good relationship

This is a very standard preposition + case pattern in Polish.

In this context, yes, that is the most natural reading.

The noun związek can mean different things depending on context, for example:

• a relationship
• an association
• a union
• a compound (in chemistry)

But with:

• w dobrym związku

the intended meaning is almost certainly in a good romantic relationship / partnership.

Literally, rozmowa means conversation or talking. In this sentence, it has a broader relationship meaning, closer to:

• conversation
• communication
• open discussion

So even though the literal word is conversation, the idea is likely that good relationships need people to talk honestly and calmly with each other.

Yes. That would be completely grammatical.

For example:

• W dobrym związku prawda, spokój i rozmowa są ważniejsze.

That version sounds a bit more straightforward and direct. The original:

• w dobrym związku ważniejsze są prawda, spokój i rozmowa

puts a bit more emphasis on ważniejsze and sounds slightly more literary or carefully styled.

So this is mainly about emphasis and rhythm, not grammar correctness.

The semicolon links two closely related complete thoughts:

1. age is not always what matters;
2. in a good relationship, other things matter more.

A semicolon is stronger than a comma but weaker than a full stop. It signals:

• these are separate clauses,
• but they belong very closely together.

You could replace it with a full stop in normal writing:

• Nie zawsze ważne jest, ile kto ma lat. W dobrym związku ważniejsze są prawda, spokój i rozmowa.

That would also be correct. The semicolon just gives the sentence a slightly more formal, polished written feel.