Gledamo meduzu kako pluta uz obalu.

Gledamo is the 1st person plural present tense of gledati (to watch / to look at).

• gledam = I watch
• gledaš = you watch
• gleda = he/she/it watches
• gledamo = we watch
• gledate = you plural / formal watch
• gledaju = they watch

So the ending -mo tells you the subject is we.

In Croatian, subject pronouns are often left out because the verb ending already shows who the subject is.

So:

• Gledamo meduzu. = We are watching a jellyfish.
• Mi gledamo meduzu. also works, but mi is usually added only for emphasis, contrast, or clarity.

For example:

• Mi gledamo meduzu, a oni gledaju brod.
  We are watching the jellyfish, but they are watching the boat.

Because meduzu is in the accusative case, which is used for the direct object of the verb.

Here, the jellyfish is the thing being watched, so you need the accusative:

• nominative: meduza = a jellyfish
• accusative: meduzu = a jellyfish (as the object)

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

• žena → ženu
• riba → ribu
• meduza → meduzu

In many contexts, kako does mean how, but after verbs of seeing, hearing, or watching, it often means something like:

• how
• as
• the way that

So in this sentence, kako pluta means how it is floating or as it floats.

With verbs of perception, this structure is very natural in Croatian:

• Vidim ga kako trči. = I see him running.
• Čujemo djecu kako pjevaju. = We hear the children singing.
• Gledamo meduzu kako pluta. = We watch the jellyfish floating.

So yes, it is literally how, but in English we often translate it more naturally as floating or as it floats.

Because Croatian usually uses a finite verb form here, not the infinitive.

• plutati = to float
• pluta = it floats / is floating

After kako, Croatian uses a normal conjugated verb:

• kako pluta
• not kako plutati

This is different from English, which often prefers an -ing form:

• English: We watch the jellyfish floating
• Croatian: Gledamo meduzu kako pluta

So Croatian is saying something closer to We watch the jellyfish as it floats.

The subject of pluta is meduza.

Even though meduzu is in the accusative in the main clause, it is still understood as the thing that is floating in the subordinate part.

So the structure is roughly:

• Gledamo meduzu = We are watching the jellyfish
• kako pluta = as it floats

In natural English, we usually do not repeat it, but Croatian also leaves it understood here.

Obalu is also in the accusative case.

The preposition uz usually takes the accusative and often means:

• along
• by
• next to
• up against

So:

• obala = coast / shore
• uz obalu = along the coast / by the shore

That is why it is obalu, not obala.

Here uz means something like along or by.

So pluta uz obalu suggests the jellyfish is floating:

• along the coast
• near the shore
• by the shore

The exact English choice depends on context, but the core idea is movement or position close to the shoreline.

Some other examples:

• Hodamo uz rijeku. = We are walking along the river.
• Kuća je uz cestu. = The house is by the road.

Yes, Croatian word order is fairly flexible.

The given sentence is natural:

• Gledamo meduzu kako pluta uz obalu.

But you may also hear:

• Gledamo kako meduza pluta uz obalu.

That version is also correct, but the structure feels a little different:

• Gledamo meduzu kako pluta... keeps meduzu closely tied to gledamo
• Gledamo kako meduza pluta... focuses more on the whole scene of the jellyfish floating

Both are understandable and natural.

Yes. Croatian present tense often covers both:

• it floats
• it is floating

So pluta can mean either, depending on context.

Likewise:

• gledamo can mean we watch or we are watching

In this sentence, the ongoing-action meaning is the natural one, so English usually uses are watching and is floating.

Both gledati and plutati are imperfective verbs.

That matters because imperfective verbs are used for:

• ongoing actions
• repeated actions
• actions viewed as a process

Here, both actions are in progress:

• we are in the middle of watching
• the jellyfish is in the middle of floating

So imperfective aspect is exactly what you would expect.

If Croatian wanted to focus on a completed, one-time result, it might use a perfective verb instead, but that would not fit this situation as naturally.

A simple English-friendly approximation is:

MEH-doo-zoo

More carefully, syllable by syllable:

• me
• du
• zu

A few helpful pronunciation notes:

• e is like e in bed
• u is like oo in food
• z is always a clear z sound

Also, Croatian stress can vary by dialect and standard pronunciation details are more nuanced, but for a learner, saying MEH-doo-zoo will be understood well.

Obala can mean a coast or a shore, depending on context.

It can be used for:

• the sea coast
• the shore/bank of a river or lake in some contexts

In this sentence, because of meduza (jellyfish), most people will naturally imagine the seashore / coastline.