Navigacija kaže da moramo skrenuti desno kod smjerokaza za jezero.

In this sentence, navigacija usually means a GPS/navigation system, like the voice on your phone or in the car.

So Navigacija kaže... means something like:

• The GPS says...
• The navigation says...

Croatian often uses navigacija this way in everyday speech.

Kaže da... is a very common Croatian structure meaning says that...

• kaže = says
• da = that

So:

• Navigacija kaže da moramo... = The GPS says that we have to...

In Croatian, da is often used to introduce a subordinate clause after verbs like:

• reći = to say
• misliti = to think
• znati = to know

English sometimes drops that, but Croatian usually keeps da in this kind of sentence.

Because Croatian verb endings already show the subject.

• moram = I must
• moraš = you must
• mora = he/she/it must
• moramo = we must
• morate = you plural / formal you must
• moraju = they must

So moramo already means we must / we have to, and adding mi is usually unnecessary unless you want emphasis.

• moramo skrenuti = we have to turn
• mi moramo skrenuti = we have to turn (emphasized)

Moramo comes from morati, which means must / have to.

In many contexts, morati can be translated either way:

• Moramo skrenuti desno. = We must turn right.
• Moramo skrenuti desno. = We have to turn right.

In everyday English, have to often sounds more natural, and that is also often the best translation here.

After morati (must / have to), Croatian normally uses the infinitive of the main verb.

So:

• moramo skrenuti = we have to turn

This is parallel to English:

• we have to turn
• we must turn

Here:

• moramo = finite/modal verb
• skrenuti = infinitive, to turn

That structure is completely normal.

This is about aspect, which is very important in Croatian.

• skrenuti = perfective
• skretati = imperfective

Very roughly:

• skrenuti focuses on the completed action: turn
• skretati focuses on the process, repetition, or ongoing action: be turning / turn repeatedly

In this sentence, the GPS is giving a single instruction about one specific action, so skrenuti is the natural choice:

• moramo skrenuti desno = we have to turn right

If you used skretati, it would sound less natural here.

Here desno is an adverb, meaning to the right / right.

After verbs of movement like skrenuti (to turn), Croatian uses adverbs such as:

• lijevo = left
• desno = right
• ravno = straight

So:

• skrenuti desno = turn right
• skrenuti lijevo = turn left
• ići ravno = go straight

By contrast, desni / desna / desno can also be adjective forms meaning right-hand depending on context, but here it is clearly the adverb.

Here kod means at, by, or near.

So:

• kod smjerokaza = at/by the signpost

In everyday Croatian, kod often gives the idea of being in the vicinity of something, not necessarily touching it exactly.

Examples:

• kod škole = near the school / by the school
• kod mosta = by the bridge
• kod semafora = at the traffic lights

So in this sentence, the meaning is that the turn happens at the point where the signpost for the lake is.

Because kod takes the genitive case, and smjerokaza is the genitive singular form of smjerokaz.

The noun is:

• smjerokaz = signpost / direction sign

Its singular forms include:

• nominative: smjerokaz
• genitive: smjerokaza

So:

• kod smjerokaza = at/by the signpost

This is a very common pattern:

• kod + genitive

Smjerokaz is a direction sign or signpost showing which way to go.

It comes from:

• smjer = direction
• -kaz related to showing/indicating

In this sentence, it means a sign that points toward the lake.

Depending on context, English might translate it as:

• signpost
• direction sign
• road sign

Here za means something like for in the sense of the sign for the lake.

So:

• smjerokaz za jezero = the signpost for the lake

This means the sign indicates the route/direction to the lake.

It does not mean that the sign is physically intended as a gift for the lake. It means the sign points toward that destination.

This use of za is common with signs and directions:

• izlaz za centar = exit for the city center
• skretanje za Zagreb = turnoff for Zagreb
• put za selo = road to the village

Here jezero is in the accusative singular.

The noun is:

• nominative: jezero
• accusative: jezero

Because jezero is a neuter inanimate noun, the nominative and accusative forms are the same, so you do not see a visible change.

The preposition za in this meaning normally takes the accusative:

• za jezero
• za grad
• za selo

So even though the form looks unchanged, it is still accusative.

Yes. Croatian word order is more flexible than English, although some versions sound more natural than others.

The original sentence is very natural:

• Navigacija kaže da moramo skrenuti desno kod smjerokaza za jezero.

You could also hear variations like:

• Navigacija kaže da kod smjerokaza za jezero moramo skrenuti desno.
• Navigacija kaže da moramo kod smjerokaza za jezero skrenuti desno.

These all mean basically the same thing, but the original order is smooth and neutral.

Croatian often moves parts of the sentence around for:

• emphasis
• rhythm
• focus

Yes, trebamo skrenuti is possible, but it is slightly different in tone.

• moramo skrenuti = we must / we have to turn
• trebamo skrenuti = we should / we need to turn

In many real-life situations, the difference is small, but moramo sounds stronger and more obligatory. Since a GPS instruction is giving a necessary route action, moramo skrenuti fits very well.

Yes, it is natural.

People might also say things like:

• GPS kaže...
• Navigacija govori...
• Piše na navigaciji da...

But Navigacija kaže... is simple, common, and idiomatic.

It personifies the device a little, just like English does in sentences such as:

• The GPS says turn right.