Hon blev först sur, men sedan märkte hon att alla bara försökte hjälpa henne.

Because blev means became/got, while var means was.

• Hon blev sur = She got annoyed / became upset
• Hon var sur = She was annoyed / upset

In this sentence, the idea is that her mood changed at first, so blev is the natural choice.

In Swedish, sur often means annoyed, irritated, upset, grumpy, not just sour in the literal taste sense.

So Hon blev först sur means something like:

• She got annoyed at first
• She was upset at first
• She got a bit grumpy at first

The exact English word depends on context, but annoyed/upset is usually a good fit here.

Först means first / at first.

In this sentence, it shows the first stage of events:

• Hon blev först sur = At first, she got annoyed

It contrasts with what happens later:

• men sedan = but then / but later

So the structure is:

• first this happened
• then something changed

They mark the sequence of events.

• först = at first / first
• sedan = then / afterwards / later

So:

• Hon blev först sur = first she became upset
• men sedan märkte hon... = but then she noticed...

Together they help tell the story in time order.

This is because Swedish has V2 word order in main clauses. That means the finite verb usually comes in the second position.

If a sentence starts with something other than the subject, like sedan, the verb comes next:

• Sedan märkte hon...

Compare:

• Hon märkte sedan... = subject first, so verb stays after the subject
• Sedan märkte hon... = time word first, so verb comes before the subject

This is very common in Swedish:

• Igår gick jag hem.
• Då såg hon honom.
• Sedan märkte hon att...

Att here means that and introduces a subordinate clause.

• hon märkte att... = she noticed that...

So the sentence breaks down like this:

• main clause: sedan märkte hon
• subordinate clause: att alla bara försökte hjälpa henne

In English, that is sometimes optional, but in Swedish att is often included in this kind of sentence.

Alla means everyone / everybody / all people.

• alla = everyone
• all usually means all in the sense of all of something in certain grammatical patterns, not everyone

So here:

• att alla... = that everyone...

Examples:

• Alla kom. = Everyone came.
• All mat är slut. = All the food is gone.

So alla is the correct form when talking about people in general.

Bara means only / just.

Here, alla bara försökte hjälpa henne means:

• everyone was just trying to help her
• everyone was only trying to help her

The word bara often comes before the thing it limits. Here it limits försökte hjälpa henne, meaning that helping her was the only thing they were trying to do.

Word placement with bara can vary a bit in Swedish, but this position is very natural.

Because försöka means to try, and it is followed by an infinitive verb:

• försöka hjälpa = try to help

In the sentence:

• försökte = past tense of försöka
• hjälpa = infinitive, help

So:

• alla bara försökte hjälpa henne = everyone was just trying to help her

This is similar to English tried to help, except Swedish does not need a separate word equivalent to to here.

Because henne is the object form of hon.

• hon = she (subject form)
• henne = her (object form)

In this sentence, she is receiving the action of helping:

• hjälpa henne = help her

Compare:

• Hon hjälper mig. = She helps me.
• Jag hjälper henne. = I help her.

Yes, märkte is the past tense of märka, which often means notice or realize depending on context.

Here it means something like:

• she noticed
• she realized

So sedan märkte hon att... can be understood as:

• but then she noticed that...
• but then she realized that...

Both are reasonable in English. The Swedish verb märka is commonly used when someone becomes aware of something.

Yes:

• Hon = she
• blev = became / got
• först = at first
• sur = annoyed / upset
• men = but
• sedan = then
• märkte = noticed / realized
• hon = she
• att = that
• alla = everyone
• bara = just / only
• försökte = tried / were trying
• hjälpa = help
• henne = her

So the structure is:

• At first she got upset
• but then she realized
• that everyone was just trying to help her

Swedish simple past often covers meanings that English might express with either:

• tried
• was/were trying

So alla bara försökte hjälpa henne can mean:

• everyone just tried to help her
• everyone was just trying to help her

In natural English, was/were trying sounds better here, but Swedish does not need a separate progressive form the way English often does. The simple past försökte is enough.