Ne želim takav posao.

In Serbian, the subject pronoun is often omitted because the verb ending already shows who is doing the action.

• želim = I want
• so Ne želim already means I do not want

You could say Ja ne želim takav posao, but ja is usually added only for emphasis, contrast, or clarity.

For example:

• Ne želim takav posao. = I don’t want that kind of job.
• Ja ne želim takav posao. = I don’t want that kind of job. (more emphatic)

Serbian normally forms negation by putting ne before the verb.

• želim = I want
• ne želim = I do not want / I don’t want

This is the standard pattern:

• Radim = I work
• Ne radim = I do not work

So in Ne želim takav posao, the ne simply negates the verb želim.

Želim is the 1st person singular present tense form of the verb želeti or željeti (depending on the standard/variant), meaning to want.

So:

• želim = I want
• želiš = you want
• želi = he/she/it wants

In this sentence, želim is used in the present tense, but just as in English, it can express a current wish or preference:

• Ne želim takav posao. = I don’t want that kind of job.

Takav means such, that kind of, or like that.

So takav posao means:

• such a job
• that kind of job
• a job like that

It describes the noun posao and agrees with it in gender, number, and case.

Related forms include:

• takav = masculine singular
• takva = feminine singular
• takvo = neuter singular
• takvi = masculine plural

Examples:

• takav čovek = such a man
• takva knjiga = such a book
• takvo mesto = such a place

Because takav is an adjective-like word, and it must agree with the noun it describes.

Here, posao is:

• masculine
• singular
• accusative (because it is the direct object of želim)

So takav also appears in the matching masculine singular accusative form.

A useful detail: with masculine inanimate nouns, the accusative singular is usually the same as the nominative singular.

That is why you see:

• posao in nominative
• posao in accusative as well

And the same happens with takav here.

Because želim takes a direct object, and that object goes in the accusative case. However, posao is a masculine inanimate noun, and in Serbian, masculine inanimate nouns usually have the same form in the nominative and accusative singular.

So:

• nominative: posao
• accusative: posao

That is why the word does not visibly change, even though it is functioning as the object.

Compare that with a masculine animate noun, where the accusative often does change:

• nominative: čovek = man
• accusative: čoveka

But with posao, there is no visible difference in the singular.

Yes. Serbian word order is more flexible than English word order, although some orders sound more neutral than others.

The most neutral version here is:

• Ne želim takav posao.

You may also hear:

• Takav posao ne želim.
  This puts more emphasis on takav posao.
• Ja ne želim takav posao.
  This emphasizes I.

So the original sentence is the most straightforward, neutral way to say it, but other orders are possible depending on emphasis.

Usually that kind of job sounds more natural in everyday English, although such a job is also possible in some contexts.

So:

• Ne želim takav posao.
  can mean
  I don’t want that kind of job.
• or more literally
  I don’t want such a job.

The best translation depends on context, but takav definitely points to a type or kind of thing.

A rough pronunciation is:

• želim ≈ ZHEH-leem
• ne ≈ neh
• takav ≈ TAH-kahv
• posao ≈ POH-sah-oh

A few useful pronunciation notes:

• ž sounds like the s in measure or vision
• j in Serbian sounds like English y
• Serbian vowels are usually clear and short, not reduced like English unstressed vowels

So želim begins with that zh sound: ZHEH-.

Usually, no—not with the same structure and meaning.

Neću is the negative of hoću (I will / I want), but in modern Serbian it is very commonly used for I won’t, and it behaves differently from ne želim.

For simple I don’t want, ne želim is the clearest and safest choice.

• Ne želim takav posao. = I don’t want that kind of job.

By contrast, neću often sounds more like refusal:

• Neću! = I won’t! / I don’t want to!

So for a sentence about preference or desire regarding a job, ne želim is the natural choice.