Hon vågar dela sin idé med gruppen, men hon vill undvika ett långt samtal om samma problem.

Because sin is a reflexive possessive. It refers back to the subject of the same clause, which here is hon.

• Hon vågar dela sin idé... = she dares share her own idea.
• Hon vågar dela hennes idé... would normally mean she dares share another woman’s idea.

So Swedish makes a distinction that English usually does not.

The forms sin / sitt / sina agree with the thing being possessed, not with the person who owns it.

Here the possessed noun is idé, which is:

• singular
• an en-word

So you use sin.

Compare:

• sin idé = her/his own idea
• sitt problem = her/his own problem
• sina idéer = her/his own ideas

Because in Swedish, a possessive already functions as a determiner, so you do not add en or ett.

So you say:

• sin idé
• min bok
• hans bil

not:

• en sin idé
• en min bok

This is similar to English: we say my book, not a my book.

With våga, Swedish very often uses the infinitive without att, especially in everyday modern Swedish.

So:

• Hon vågar dela sin idé = natural and standard

You may sometimes encounter att after våga, but learners should usually prefer the version without it in sentences like this.

Because the normal pattern is dela något med någon = share something with someone.

Here:

• dela = share
• sin idé = the thing being shared
• med gruppen = with the group

So med is the standard preposition after dela in this meaning.

Because gruppen is the definite form: the group.

In Swedish, definiteness is often shown by adding an ending to the noun:

• en grupp = a group
• gruppen = the group

So med gruppen means with the group.

Because samtal is an ett-word (a neuter noun).

That affects both the article and the adjective:

• ett = the correct indefinite article
• långt = lång
  • -t, which is the neuter singular form

So:

• ett långt samtal = a long conversation

Compare with an en-word:

• en lång diskussion

Because samma is normally indeclinable in modern Swedish. That means it keeps the same form regardless of gender or number.

Examples:

• samma idé
• samma problem
• samma idéer

Also, Swedish does not use a separate word for the here, even though English says the same problem. So samma problem is the normal Swedish expression.

Here om means about, not if.

So:

• ett långt samtal om samma problem = a long conversation about the same problem

This is very common after nouns like:

• samtal om = conversation about
• diskussion om = discussion about
• fråga om = question about

Because men is a coordinating conjunction, and it introduces a new main clause.

Swedish main clauses follow the V2 rule, meaning the finite verb comes in the second position. In this clause:

• hon = first element
• vill = second element

So the word order is correct.

A useful point: men itself does not count as the first clause element in the V2 pattern.

Because undvika is a transitive verb. It takes a direct object.

So Swedish says:

• undvika något = avoid something

Here the object is:

• ett långt samtal om samma problem

So the structure is completely normal:

• hon vill undvika ett långt samtal...

There is no extra preposition needed after undvika.