Hon trivs på sin nya arbetsplats, eftersom hennes kollegor bryr sig om varandra.

Trivs is the present tense of trivas, a very common Swedish verb meaning to enjoy oneself, to feel comfortable, or to thrive in a place or situation.

So Hon trivs means something like:

• She is happy
• She feels comfortable
• She likes being there

It is an -s verb in its dictionary form: trivas.
That means its present tense is also built with -s:

• infinitive: trivas
• present: trivs
• past: trivdes
• supine: trivts

This kind of verb can feel unusual to English speakers, because it looks a bit passive, but here it is just the normal form of the verb.

Swedish often uses på with places like workplaces, school, the office, and similar environments.

So:

• på jobbet = at work
• på kontoret = at the office
• på skolan = at the school
• på sin nya arbetsplats = at her new workplace

English often uses at, while Swedish frequently uses på in these cases. It is something you largely have to get used to as a language pattern.

This is one of the most important grammar points in Swedish.

Sin/sitt/sina is a reflexive possessive. It is used when the possessor is the same as the subject of the clause.

Here, the subject is Hon. So if we mean her own new workplace, Swedish uses sin:

• Hon trivs på sin nya arbetsplats. = She enjoys her new workplace.
  Meaning: the workplace is hers.

If you say:

• Hon trivs på hennes nya arbetsplats.

that normally suggests the workplace belongs to or is associated with some other woman, not the subject hon.

So:

• sin = her own
• hennes = someone else’s her

Because arbetsplats is an en-word and singular.

Swedish reflexive possessives agree with the noun they describe:

• sin for en-word singular
• sitt for ett-word singular
• sina for plural

Examples:

• sin bok = his/her own book
• sitt hus = his/her own house
• sina böcker = his/her own books

Since arbetsplats is singular and an en-word, the correct form is sin nya arbetsplats.

Because Swedish forms compound nouns very freely, much more than English does.

Arbetsplats is made from:

• arbete = work
• plats = place

Together: arbetsplats = workplace

This is completely normal in Swedish. English often writes similar ideas as two words, but Swedish usually joins them into one:

• arbetsplats = workplace
• sjukhus = hospital
• sommarjobb = summer job

A useful habit when learning Swedish is to look for smaller parts inside long words.

Because here Swedish is not using a reflexive possessive inside the subordinate clause.

In eftersom hennes kollegor bryr sig om varandra, the phrase hennes kollegor means her colleagues.

If you used sina kollegor, it would normally refer back to the subject of that clause. But the subject of that clause is kollegor, so sina kollegor would create a different and awkward meaning, something more like their own colleagues.

So Swedish uses:

• hennes kollegor = her colleagues

not

• sina kollegor

This is a very common point of confusion for English speakers: sin/sitt/sina only refers back to the subject of its own clause.

Bryr sig om means cares about.

The full verb is bry sig om, which is a reflexive expression:

• bry = base verb
• sig = reflexive pronoun
• om = preposition

You usually learn it as a whole unit:

• Jag bryr mig om dig. = I care about you.
• Hon bryr sig om sina barn. = She cares about her children.

So in your sentence:

• hennes kollegor bryr sig om varandra
  = her colleagues care about each other

It is best to memorize bry sig om as one expression, not word by word.

Because bry sig om is a reflexive verb expression in Swedish. The sig is part of the normal structure.

The reflexive pronoun changes with the subject:

• jag bryr mig om = I care about
• du bryr dig om = you care about
• han/hon bryr sig om = he/she cares about
• vi bryr oss om = we care about
• ni bryr er om = you (plural) care about
• de bryr sig om = they care about

English does not use a reflexive pronoun here, so this can feel strange at first. But in Swedish, it is required.

Varandra means each other or one another.

It is used when a plural subject does something mutually:

• De hjälper varandra. = They help each other.
• Vi känner varandra. = We know each other.
• Hennes kollegor bryr sig om varandra. = Her colleagues care about each other.

This is different from sig, which refers back reflexively to the subject.
Here the meaning is not that each colleague cares only about himself or herself, but that they care for one another.

Because eftersom introduces a subordinate clause, and in Swedish subordinate clauses the word order is generally:

subject + verb

So:

• eftersom hennes kollegor bryr sig om varandra

not:

• eftersom bryr hennes kollegor sig om varandra

In Swedish, inversion is common in main clauses after something is placed first:

• I dag trivs hon bättre.

But after a subordinating word like eftersom, att, när, om, därför att, Swedish usually keeps normal subject-verb order.

Not always. In modern Swedish, a comma before a subordinate clause is often optional, especially in shorter sentences.

So both of these are possible:

• Hon trivs på sin nya arbetsplats eftersom hennes kollegor bryr sig om varandra.
• Hon trivs på sin nya arbetsplats, eftersom hennes kollegor bryr sig om varandra.

The comma can make the sentence a little easier to read, but it is not strictly necessary in every case.

Sometimes yes, but eftersom is especially clear for because.

• eftersom = because / since
• för att can mean because, but it can also mean in order to

Because of that, eftersom is often the clearer choice when giving a reason.

So in this sentence:

• Hon trivs ... eftersom hennes kollegor bryr sig om varandra

is a very natural way to say She enjoys it there because her colleagues care about each other.

Using för att is possible in many contexts, but eftersom avoids ambiguity.