Medarbetaren bidrog till ett bra samarbete.

Because -en makes the noun definite singular.

• en medarbetare = an employee / a co-worker
• medarbetaren = the employee / the co-worker

So medarbetaren means the employee.

A useful detail: medarbetare is one of those nouns that has the same form in the indefinite singular and plural:

• en medarbetare = an employee
• flera medarbetare = several employees
• medarbetaren = the employee
• medarbetarna = the employees

Bidrog is the past tense of bidra.

The forms are:

• att bidra = to contribute
• bidrar = contributes / is contributing
• bidrog = contributed
• har bidragit = has contributed

So:

• Medarbetaren bidrog ... = The employee contributed ...

This verb is a little irregular, so you have to learn bidrog rather than building it with a regular ending.

Because Swedish normally uses the pattern bidra till when you mean contribute to something.

So:

• bidra till något = contribute to something

Examples:

• bidra till ett bra resultat = contribute to a good result
• bidra till förändring = contribute to change
• bidra till ett bra samarbete = contribute to good collaboration / a good working relationship

So till is not optional here; it is the normal preposition that goes with bidra in this meaning.

Because samarbete is an ett-word (a neuter noun), not an en-word.

So:

• ett samarbete = a collaboration / a cooperation
• samarbetet = the collaboration

That is why the sentence has:

• till ett bra samarbete

not:

• till en bra samarbete

When learning Swedish nouns, it is important to learn the article together with the noun:

• ett samarbete
• en medarbetare

Normally, many Swedish adjectives do change form depending on the noun:

• en stor bil
• ett stort hus
• stora hus

But bra is special: it usually does not change.

So you say:

• en bra idé
• ett bra samarbete
• bra kollegor

This is completely normal. Bra stays bra.

Samarbete means cooperation, collaboration, or sometimes working together.

It comes from:

• sam- = together
• arbete = work

So literally it has the idea of working together.

In this sentence, ett bra samarbete suggests good cooperation or a good working relationship, depending on context.

Yes. This is normal Swedish main-clause word order.

The basic pattern here is:

• subject
  • verb
    • rest of the sentence

So:

• Medarbetaren = subject
• bidrog = verb
• till ett bra samarbete = prepositional phrase

Swedish is a V2 language, which means the finite verb usually comes in the second position in a main clause.

This sentence follows that rule perfectly:

• first position: Medarbetaren
• second position: bidrog

You could also move another element to the front, but then the verb still stays second:

• Till ett bra samarbete bidrog medarbetaren.

That version is more marked or stylistic, but grammatically possible.

Sometimes, yes, but be careful.

Medarbetare often means:

• employee
• member of staff
• co-worker / colleague in some contexts

In workplace Swedish, it is often used in a fairly broad, positive-sounding way for someone who works in an organization. In many business contexts, employee is the safest translation.

So in this sentence, the employee contributed to a good collaboration is a very natural translation, but the co-worker contributed to good cooperation could also fit depending on the situation.

In ordinary Swedish, with a singular countable noun like samarbete, you usually need an article:

• ett bra samarbete

That is the normal full phrase.

Without ett, bra samarbete can appear in special styles, such as headings, notes, or very abstract phrasing, but in a standard sentence this version is the natural one:

• Medarbetaren bidrog till ett bra samarbete.

So for most learners, the safe rule is: use ett with samarbete when you mean a good collaboration.

Here are some useful versions:

• Medarbetaren bidrar till ett bra samarbete.
  = The employee contributes to a good collaboration.

• Medarbetaren bidrog till ett bra samarbete.
  = The employee contributed to a good collaboration.

• Medarbetaren har bidragit till ett bra samarbete.
  = The employee has contributed to a good collaboration.

This is a good way to learn the verb pattern:

• bidra
• bidrar
• bidrog
• bidragit