Prema prognozi očekujemo maglu.

Here prema means according to.

So Prema prognozi = According to the forecast.

Be careful: prema can also mean toward in other contexts, but in this sentence it clearly means according to / based on.

Because prema takes the dative case.

The base form is prognoza = forecast.
After prema, it changes to the dative singular:

• nominative: prognoza
• dative: prognozi

So:

• prema prognozi = according to the forecast

Yes, in this context it almost certainly means the weather forecast.

Serbian often leaves out words that are obvious from context. So prognoza by itself can mean forecast, and in everyday use it often refers to the weather forecast unless something else is specified.

A fuller version could be:

• Prema vremenskoj prognozi, očekujemo maglu.

That literally means According to the weather forecast, we expect fog.

Yes. It is related, but the meaning is different.

• čekati = to wait
• očekivati = to expect

So očekujemo means we expect.

Even though the words are related historically, you should learn them as separate meanings:

• Čekamo autobus. = We are waiting for the bus.
• Očekujemo kišu. = We expect rain.

Očekujemo is:

• 1st person plural
• present tense
• from the verb očekivati

So it literally means we expect.

The ending -mo shows we.

Because maglu is the accusative singular form, and it is the direct object of očekujemo.

The noun is:

• nominative: magla = fog
• accusative: maglu

Since we expect fog, fog is what is being expected, so Serbian uses the accusative:

• očekujemo maglu

This is very common with feminine nouns ending in -a:

• nominative: kiša

• accusative: kišu

• nominative: magla
• accusative: maglu

Grammatically, očekujemo is present tense, but the meaning is often future-oriented.

In weather-style language, Serbian often uses the present tense to talk about something expected soon:

• Prema prognozi očekujemo maglu. = According to the forecast, we expect fog.

This usually means fog is expected later / soon, not necessarily that it is happening right now.

Because Serbian usually does not need subject pronouns when the verb ending already shows the subject.

Here, očekujemo already tells you the subject is we.

So:

• Očekujemo maglu. = We expect fog.

You could add mi for emphasis:

• Mi očekujemo maglu.

But in a neutral sentence, it is normally left out.

Because Serbian does not have articles like a or the.

Whether something is definite or indefinite is understood from context.

So:

• prognozi can mean the forecast
• maglu can mean fog or sometimes the fog, depending on context

In this sentence, English naturally uses the forecast, but Serbian does not need a separate word for the.

Yes, Serbian word order is fairly flexible.

The neutral order here is:

• Prema prognozi očekujemo maglu.

But other orders are possible, depending on emphasis:

• Maglu očekujemo prema prognozi.
• Prema prognozi maglu očekujemo.

These alternatives are grammatical, but the original sentence sounds the most natural and neutral in ordinary usage.

A rough pronunciation is oh-cheh-KOO-yeh-moh.

A few helpful sound notes:

• č sounds like ch in church
• j sounds like y in yes

So:

• o-če-ku-je-mo

Also, Serbian pronunciation is usually quite regular, so once you know the letters, the pronunciation is predictable.