Što god je napisano u preporuci, pažljivo pročitajte.

Što god means whatever or no matter what.

In this sentence, it introduces the idea of any possible thing that is written in the recommendation. So the structure is:

• što = what
• god = a particle that adds the sense of ever / no matter

Together, što god = whatever.

No. god here is not the noun God.

It is a small grammatical particle used in expressions like:

• što god = whatever
• tko god = whoever
• gdje god = wherever
• kad god = whenever

So in this sentence, god just helps create that -ever meaning.

Yes, in many spoken varieties of Croatian, šta god is common and natural.

But što god is usually considered more standard in formal Croatian. Since your sentence sounds fairly neutral or formal, što god fits very well.

So:

• što god = standard/neutral
• šta god = common in speech, depending on region and style

Je napisano is a passive construction.

It is made of:

• je = is (3rd person singular of biti, to be)
• napisano = written (past passive participle of napisati)

So je napisano literally means is written or sometimes has been written, depending on context.

Because što god refers to an unspecified thing/content, and Croatian treats that as neuter singular.

So the participle agrees in neuter singular:

• napisano = neuter singular

You can think of it as something like an implied ono što = that which / what.

That is why napisano is the natural form here.

Preporuci is in the locative singular.

After the preposition u, Croatian uses:

• locative for location: in
• accusative for motion toward/into something

Here the meaning is in the recommendation, so locative is required:

• u preporuci = in the recommendation

If it were motion, Croatian would use a different form.

Preporuka usually means recommendation, but the exact English translation depends on context.

Possible translations include:

• recommendation
• reference
• letter of recommendation
• sometimes something closer to referral

So the Croatian word is broader than one single English equivalent. The context tells you which English word fits best.

Pročitajte is the imperative form of pročitati.

It is the form used for:

• you all, read
• or please read when addressing one person politely

So it can be:

• 2nd person plural imperative
• or formal singular imperative

That is why this sentence can sound like an instruction, advice, or polite command.

This is a question of aspect, which is very important in Croatian.

• pročitati = to read through / to read completely → perfective
• čitati = to read / to be reading / to read habitually → imperfective

In an instruction like this, Croatian often prefers the perfective imperative when the speaker wants the action to be completed:

• pročitajte = read it through / make sure you read it

If you said čitajte, it would sound more like:

• be reading
• read in general
• keep reading

So pročitajte is the better choice here.

Because pažljivo is an adverb, and it modifies the verb pročitajte.

It means carefully.

Compare:

• pažljiv = careful → adjective
• pažljivo = carefully → adverb

Here the sentence is telling you how to read, so Croatian needs the adverb:

• pažljivo pročitajte = read carefully

Because Što god je napisano u preporuci is a subordinate clause placed before the main clause.

Structure:

• subordinate clause: Što god je napisano u preporuci
• main clause: pažljivo pročitajte

Croatian normally separates a fronted subordinate clause from the main clause with a comma.

If you changed the word order, you could say:

• Pažljivo pročitajte što god je napisano u preporuci.

In that version, you normally would not put a comma before the subordinate clause.

Yes. Croatian word order is fairly flexible.

Your sentence is correct, but a very natural alternative is:

• Pažljivo pročitajte što god je napisano u preporuci.

Both versions are grammatical. The difference is mostly in emphasis:

• Što god je napisano u preporuci, pažljivo pročitajte.
  This puts strong focus on whatever is written in the recommendation.

• Pažljivo pročitajte što god je napisano u preporuci.
  This sounds a bit more neutral and straightforward.