Biljka izgleda užasno bez vode.

• biljka = plant
• izgleda = looks / seems
• užasno = terribly / awful / terrible here, depending on how you translate it naturally
• bez = without
• vode = water in the form required after bez

So word-for-word, it is roughly Plant looks terribly without water, but natural English is The plant looks terrible without water.

Croatian does not have articles like a and the.

So biljka can mean:

• a plant
• the plant

You understand which one is meant from context. In this sentence, English usually says the plant, but Croatian simply uses biljka.

Izgleda is the 3rd person singular present tense of izgledati.

That means:

• ja izgledam = I look
• ti izgledaš = you look
• on/ona/ono izgleda = he/she/it looks

Since biljka is singular, the verb is also singular: biljka izgleda = the plant looks.

Good question. Here užasno is functioning adverbially, meaning something like terribly or awfully, even though in English we often translate the whole phrase as looks terrible.

Compare:

• Biljka je užasna. = The plant is terrible.
  Here užasna is an adjective agreeing with feminine biljka.
• Biljka izgleda užasno. = The plant looks terrible / looks awful.
  Here užasno modifies izgleda and behaves like an adverb.

This is very common in Croatian after verbs like izgledati, zvučati, osjećati se, etc.

Because bez requires the genitive case.

The basic form is:

• voda = water

After bez, you need genitive:

• bez vode = without water

So the ending changes because of grammar, not because the meaning changes.

Yes, bez is a preposition that normally takes the genitive.

Examples:

• bez vode = without water
• bez novca = without money
• bez prijatelja = without a friend / without friends
• bez problema = without problems

So when you see bez, you should expect the next noun to be in genitive.

Yes, here bez vode is understood as without water in a general, mass-noun sense.

Grammatically, vode can also look like other forms in Croatian, but in this sentence the intended meaning is singular/genitive after bez:

• voda = water
• bez vode = without water

Since water is usually treated as an uncountable substance, English also does not show singular/plural in the same way here.

Croatian word order is fairly flexible.

The neutral order here is:

• Biljka izgleda užasno bez vode.

But you could also say:

• Bez vode biljka izgleda užasno.
• Biljka bez vode izgleda užasno.

These all mean roughly the same thing, but the emphasis shifts a little:

• starting with bez vode emphasizes the condition without water
• keeping biljka first is the most straightforward, neutral structure

They are similar, but not identical.

• Biljka izgleda užasno. = The plant looks terrible.
  This describes appearance: maybe it is drooping, dry, unhealthy-looking.
• Biljka je užasna. = The plant is terrible.
  This sounds stronger and more direct, as if you are judging the plant itself.

So with plants, izgleda užasno is usually the more natural choice when talking about condition or appearance.

Yes. Izgledati can refer to:

1. appearance
   
   • Biljka izgleda zdravo. = The plant looks healthy.
2. impression / seeming
   
   • Izgleda umorno. = He/She looks tired.
   • Izgleda da će padati kiša. = It looks like it will rain.

In your sentence, it is clearly about appearance.

Yes, užasno is fairly strong. It means something like:

• terribly
• awfully
• horribly

In this sentence it suggests the plant looks really bad.

Milder alternatives would be:

• loše = badly / poorly
  Biljka izgleda loše bez vode.
• slabo = weakly / badly, depending on context
• uvenulo = wilted, if you want something more specific

So užasno is natural, but emotionally stronger than loše.

The tricky part is lj.

In Croatian, lj is a single sound, similar to the lli in some pronunciations of million, though not exactly the same for every English speaker.

So biljka is roughly:

• BIL-yka

with:

• stress usually on the first syllable
• a clear lj sound, not a full English l + j sequence

Also:

• ž in užasno sounds like the s in measure
• g in izgleda is always a hard g

By itself, bez vode simply means without water. The exact meaning depends on context.

It could mean:

• it has not been watered
• it is lacking water
• it is in a place or condition without water

In normal everyday use with a plant, people will usually understand it as because it has no water / because it hasn’t been watered.

Yes, absolutely.

• Biljka izgleda užasno bez vode. = The plant looks terrible without water.
• Biljka izgleda loše bez vode. = The plant looks bad without water.

Both are correct. The difference is just intensity:

• loše = milder
• užasno = stronger, more dramatic