Nasza solistka ma mocny głos, ale ten solista śpiewa ciszej.

Because some Polish nouns for male people end in -a even though they are masculine in grammar.

So in ten solista:

• solista = a masculine noun meaning male soloist
• ten shows that it is masculine singular nominative

This is similar to other masculine nouns like:

• poeta = poet
• artysta = artist
• kolega = male friend/classmate

So the ending -a does not always mean the noun is feminine.

They are gendered forms of the same role:

• solistka = female soloist
• solista = male soloist

In this sentence:

• Nasza solistka = our female soloist
• ten solista = this male soloist

This kind of male/female noun pair is very common in Polish.

Both words must agree with the noun they go with.

• solistka is feminine singular, so our becomes nasza
• solista is masculine singular, so this becomes ten

Polish words like possessives, demonstratives, and adjectives change their endings to match:

• gender
• number
• case

So the forms are:

• nasza solistka = feminine singular
• ten solista = masculine singular

Because głos is the direct object of ma (has), so it is in the accusative case.

However, for a masculine inanimate noun like głos, the accusative singular looks the same as the nominative singular.

So:

• nominative: mocny głos
• accusative: mocny głos

That is why after ma you still see mocny głos.

By contrast, with some other genders or noun types, the form would change more obviously.

Ciszej is the comparative adverb of cicho.

• cicho = quietly / softly
• ciszej = more quietly / more softly

It describes how someone sings:

• śpiewa cicho = sings quietly
• śpiewa ciszej = sings more quietly

So ciszej is not an adjective here; it is an adverb.

You might be understood, but ciszej is the normal and natural form.

In Polish, many common adverbs form the comparative with a special one-word form:

• cicho → ciszej
• głośno → głośniej
• szybko → szybciej

Using bardziej + adverb/adjective is possible in some situations, but when a simple comparative exists, Polish usually prefers it.

Because Polish has no articles like English a, an, or the.

So:

• ma mocny głos can mean has a strong voice
• depending on context, it could also be understood as has the strong voice, though English usually chooses one article

Polish relies on context, word order, and extra words like ten when needed.

Yes, it often can be.

• ale ten solista śpiewa ciszej = but this soloist sings more quietly
• ale solista śpiewa ciszej = but the/that soloist sings more quietly, depending on context

Adding ten makes the reference more definite or contrastive, a bit like pointing someone out:

• this soloist
• that particular soloist

So ten is not always required, but it adds emphasis or clarity.

Not completely. Polish word order is more flexible than English, although the version in the sentence is very natural.

Standard order here is:

• Nasza solistka ma mocny głos
• ale ten solista śpiewa ciszej

You could move words around for emphasis, but that changes what sounds highlighted. For example:

• Ten solista ciszej śpiewa sounds more marked
• Ciszej śpiewa ten solista strongly emphasizes this soloist

So the original sentence is a good neutral pattern for learners.

Ale means but and joins two contrasting ideas.

Here the contrast is:

• one singer has a strong voice
• the other sings more quietly

So ale works just like English but in many sentences.

A rough guide:

• ciszej sounds approximately like CHEE-shei
• śpiewa sounds approximately like SHPYE-va

A few helpful details:

• ci before a vowel often sounds like a soft ć / ch-like sound
• sz sounds like English sh
• ś is a softer sh sound
• w in Polish sounds like English v

So:

• głos sounds roughly like gwohs
• solista sounds roughly like so-LEE-sta
• solistka sounds roughly like so-LEEST-ka

Because nasza means our, and it agrees with solistka.

Possessive words also change for gender, number, and case. For feminine singular nominative, you get forms like:

• moja solistka = my female soloist
• nasza solistka = our female soloist
• ta solistka = this female soloist

So nasza is simply the correct form of our for a feminine singular noun here.