İş güvencesi benim için önemli.

Because iş güvencesi is a noun compound in Turkish.

The pattern is often:

noun + noun-(s)I

So here:

• iş = work, job
• güvence = security, assurance
• güvencesi = the second noun with the compound suffix

Together, iş güvencesi means job security or employment security.

That -si on güvence is normal in this kind of structure. It does not mean his/her here; it is part of the noun-compound pattern.

It is the third-person possessive-looking suffix that appears in many Turkish noun compounds.

With vowel harmony, this suffix can appear as -ı, -i, -u, -ü, and after a vowel it usually takes a buffer s:

• kapı → kapısı
• araba → arabası
• güvence → güvencesi

So iş güvencesi follows the same pattern.

A useful way to think about it is:

• English often uses job security
• Turkish often uses iş güvencesi

No. They are related, but they mean different things.

• iş güvencesi = job security
  The idea that your job is stable and protected

• iş güvenliği = workplace safety or occupational safety
  The idea of being safe at work physically

This is a very important distinction for learners, because both involve iş and a word related to safety/security, but they are not interchangeable.

Because with personal pronouns, Turkish normally uses the genitive form before için:

• benim için = for me
• senin için = for you
• onun için = for him/her/it

So ben için is not standard Turkish here.

This is something learners often just need to memorize:

• benim için
• senin için
• bizim için
• sizin için
• onlar için is also common, though pronouns behave a little differently in some contexts

Here, için means for or to in the sense of from someone’s point of view.

So:

• benim için önemli = important for me / important to me

It does not mean physical direction like to in I am going to school.
It expresses relevance, value, or importance from a person’s perspective.

Because Turkish often leaves out the present-tense to be in third-person sentences.

So:

• İş güvencesi benim için önemli.

literally looks like:

• Job security for me important

but it naturally means:

• Job security is important for me.

This is completely normal Turkish.

A more formal or emphatic version could be:

• İş güvencesi benim için önemlidir.

Here -dir adds a formal, written, or definite tone.

Yes. Önemli is an adjective meaning important.

In this sentence, it is used as a predicate adjective, meaning it describes the subject:

• İş güvencesi ... önemli = Job security ... is important

It can also directly modify nouns:

• önemli bir konu = an important issue
• önemli insanlar = important people

So the word itself is an adjective, but in this sentence it functions like is important in English.

Yes. Turkish word order is flexible, and changing it usually changes the emphasis, not the basic meaning.

For example:

• İş güvencesi benim için önemli.
  Neutral, natural

• Benim için iş güvencesi önemli.
  Stronger emphasis on for me

Both are correct.

Turkish often places the most important or newest information near the end, so the final word önemli gets natural emphasis.

Not if you want to keep the meaning for me.

You need the full phrase:

• benim için = for me

So you cannot normally say just:

• için önemli

without saying for whom.

However, you can remove the whole phrase if the meaning becomes more general:

• İş güvencesi önemli. = Job security is important.

That no longer means important for me specifically. It becomes a general statement.

No, not in standard Turkish.

For this idea, Turkish normally uses:

• benim için önemli

not:

• bana önemli

So if you want to say important to me or important for me, use X için önemli:

• Benim için önemli.
• Senin için önemli mi?
• Bu konu bizim için önemli.

Benim is the genitive form of ben.

• ben = I
• benim = my / of me

In benim için, that genitive form is the normal one used with için when the word is a personal pronoun.

So even though English says for me, Turkish says something closer to of me for in structure.

That is why learners should memorize benim için as a set phrase.

Yes, absolutely.

Adding çok simply makes it stronger:

• İş güvencesi benim için önemli. = Job security is important for me.
• İş güvencesi benim için çok önemli. = Job security is very important for me.

This is a very natural extension of the original sentence.