kanozyo ha tomodati no tiimu wo ookina koe de ouensite ita ga, sono tiimu ha makete simatta.

は marks 彼女 as the topic of the sentence.

So 彼女は means something like as for her... or she... in natural English.

It does not just mean grammatical subject in the same way English does. It sets up her as the person we are talking about, and then the sentence tells us what happened in relation to her.

友達のチーム means her friend’s team or the team of her friend.

The particle の connects nouns and often shows possession or association.

• 友達 = friend
• 友達のチーム = friend’s team

Depending on context, 友達 could also be plural in Japanese, so in some situations it might mean her friends’ team, but many learners will first understand it as her friend’s team.

Because 応援する takes a direct object, and that object is marked by を.

So:

• チームを応援する = to cheer for the team / support the team

Even though English often uses for in cheer for, Japanese uses を here because the team is the thing receiving the action of support.

Both 大きな声 and 大きい声 are possible, and both mean a loud voice.

But 大きな is a special form that can only come directly before a noun. It often sounds slightly more set or natural in certain common expressions.

So:

• 大きな声で = in a loud voice / loudly

This is a very common phrase in Japanese.

Here, で shows the means or manner of the action.

So 大きな声で応援していた means she was cheering with a loud voice, or more naturally, cheering loudly.

This で is not location here. It tells you how the cheering was done.

応援していた is the past progressive / continuing-state form, while 応援した is simple past.

• 応援した = cheered
• 応援していた = was cheering / had been cheering

In this sentence, 応援していた gives background: she was in the middle of cheering, but then the next event happened — the team lost.

So the sentence has a natural flow like:

• She was cheering for the team, but...
• the team ended up losing.

Here が means but.

It connects the two clauses:

• 彼女は友達のチームを大きな声で応援していた
• そのチームは負けてしまった

So the whole structure is:

• She was cheering loudly for her friend’s team, but that team lost.

This が is a written or slightly formal way to say but. In casual speech, learners may more often see けど or けれど.

Because once the team has already been mentioned, Japanese often refers back to it with その.

• そのチーム = that team

Here it means that team we just mentioned.

This avoids repetition and sounds natural. It works much like English using that team after it has already been introduced.

This second は marks that team as the topic of the second clause.

The sentence first talks about her, then shifts focus to the team:

1. As for her, she was cheering loudly.
2. As for that team, it lost.

Japanese often uses は this way to organize information and shift focus smoothly between parts of a sentence.

負けてしまった is based on 負ける and adds しまう.

• 負けた = lost
• 負けてしまった = ended up losing / unfortunately lost / lost completely

The しまう part often adds one of these feelings:

• completion
• regret
• disappointment
• an unfortunate result

In this sentence, it suggests that the loss was disappointing or unfortunate, which fits well because she had been cheering for them.

Not exactly in a simple English-style way.

At the beginning, 彼女は is the topic of the first clause. In the second clause, そのチームは becomes the topic.

So the sentence shifts focus:

• First clause: about her
• Second clause: about that team

This is very normal in Japanese. A sentence can contain more than one は-marked topic across different clauses.

Yes. Japanese nouns usually do not show singular vs. plural clearly unless the context makes it clear.

So 友達 can mean:

• friend
• friends

That means 友達のチーム could theoretically be:

• a friend’s team
• friends’ team

But in many textbook-style examples, learners will usually interpret it as her friend’s team unless there is context suggesting multiple friends.

Those spaces are usually just for learners.

Normal Japanese writing does not normally use spaces between words like this. The sentence would normally be written as:

彼女は友達のチームを大きな声で応援していたが、そのチームは負けてしまった。

The spaces are only there to make the structure easier to see.