Wierzę w naszą drużynę.

Because in Polish there are two closely related patterns:

• wierzyć komuś / czemuś
  • dative = to believe someone / trust someone
• wierzyć w kogoś / w coś
  • accusative = to believe in someone / something

So:

• Wierzę ci. = I believe you / I trust you.
• Wierzę w naszą drużynę. = I believe in our team.

In your sentence, the meaning is believe in, so Polish uses w + the accusative case.

The dictionary form is wierzyć, meaning to believe.

Wierzę is the 1st person singular present tense form, so it means I believe.

A few present-tense forms are:

• ja wierzę = I believe
• ty wierzysz = you believe
• on / ona wierzy = he / she believes
• my wierzymy = we believe
• wy wierzycie = you all believe
• oni / one wierzą = they believe

In the sentence Wierzę w naszą drużynę, the subject ja is omitted, because Polish often drops subject pronouns when they are clear from the verb ending.

Because naszą is the correct form of nasza for the accusative singular feminine.

The noun drużyna is:

• feminine
• singular
• here used in the accusative because it follows w in the pattern wierzyć w kogoś/coś

So the adjective/pronoun must match it:

• nominative: nasza drużyna = our team
• accusative: naszą drużynę = our team

That is why the sentence uses naszą drużynę.

Drużynę is accusative singular.

The basic form is drużyna. But after wierzyć w you need the accusative:

• nominative: drużyna
• accusative: drużynę

So:

• Nasza drużyna jest silna. = Our team is strong.
• Wierzę w naszą drużynę. = I believe in our team.

This is a very common feature of Polish: nouns often change form depending on their grammatical role in the sentence.

Not if you want to say I believe in our team.

Wierzę naszej drużynie uses wierzyć komuś/czemuś, which means something more like:

• I believe our team
• I trust our team

That is a different structure and a slightly different meaning.

Compare:

• Wierzę w naszą drużynę. = I believe in our team.
• Wierzę naszej drużynie. = I believe our team / I trust our team.

Both can be grammatically correct, but they do not mean exactly the same thing.

Drużyna usually means team, often especially in contexts like:

• sports
• competitions
• organized groups playing together

So in many cases it strongly suggests a sports team.

Depending on context, Polish can also use other words such as:

• zespół = team, group, band, ensemble
• ekipa = crew, squad, team
• drużyna = team, especially a coordinated playing or competing team

In your sentence, drużyna sounds very natural for a team you support or have faith in, especially in sports.

Because Polish often leaves out subject pronouns when the verb already makes the subject clear.

Wierzę already means I believe, so ja is not necessary.

You could say:

• Ja wierzę w naszą drużynę.

But that usually adds emphasis, like:

• I believe in our team.
• As for me, I do believe in our team.

So the version without ja is the neutral, natural one.

Yes. Polish word order is more flexible than English, because case endings show grammatical relationships.

The neutral order here is:

• Wierzę w naszą drużynę.

But you may also hear:

• W naszą drużynę wierzę.

This puts more emphasis on our team, as if contrasting it with something else.

For example:

• W trenera nie wierzę, ale w naszą drużynę wierzę. = I don’t believe in the coach, but I do believe in our team.

So the meaning stays basically the same, but the emphasis changes.

A rough pronunciation guide:

• wierzę ≈ VYEH-zheh
• drużynę ≈ droo-ZHI-neh (with a nasalized final ę)

A few helpful details:

• w in Polish sounds like English v
• rz usually sounds like the zh in measure
• ż also sounds like zh
• final ę is often not pronounced as a full nasal vowel in everyday speech; it may sound closer to e or eh with some nasal coloring

So in natural speech, drużynę may sound a bit like droo-ZHI-ne.

Yes, very natural.

It sounds like something someone would say:

• before a match
• to show support
• to express confidence
• in a motivational context

It means you have faith or confidence in the team.

Similar natural sentences:

• Wierzę w ciebie. = I believe in you.
• Wierzymy w naszą drużynę. = We believe in our team.
• Naprawdę wierzę w ten zespół. = I really believe in this team.

No. W can take different cases depending on meaning.

With movement toward / into or in expressions like wierzyć w, it takes the accusative:

• wchodzę w dom = I enter the house
• wierzę w sukces = I believe in success

With location in / inside, it usually takes the locative:

• w domu = in the house
• w drużynie = in the team

So here, the accusative is not about physical movement; it is required by the expression wierzyć w kogoś/coś.

It would be:

• Wierzymy w naszą drużynę.

Only the verb changes:

• wierzę = I believe
• wierzymy = we believe

The phrase w naszą drużynę stays the same, because our team is still singular and still in the accusative.