Ova kava je gorka bez šećera.

Because kava is a feminine singular noun in Croatian, and the demonstrative ovaj / ova / ovo must agree with the noun’s gender.

• ovaj = masculine
• ova = feminine
• ovo = neuter

So:

• ova kava = this coffee

The same agreement pattern appears with adjectives too.

Because gorka is an adjective describing kava, and Croatian adjectives must agree with the noun in gender, number, and case.

Since kava is:

• feminine
• singular
• nominative (the subject of the sentence)

the adjective must also be feminine singular nominative:

• masculine: gorak
• feminine: gorka
• neuter: gorko

So:

• Ova kava je gorka. = This coffee is bitter.

Je means is. It is the 3rd person singular present tense of the verb biti (to be).

So the sentence structure is:

• Ova kava = this coffee
• je = is
• gorka = bitter
• bez šećera = without sugar

Croatian often uses forms of biti the same way English uses to be in sentences like The coffee is bitter.

Because the preposition bez (without) requires the genitive case.

The basic dictionary form is:

• šećer = sugar

But after bez, it changes to the genitive singular:

• bez šećera = without sugar

This is a very common pattern in Croatian:

• bez vode = without water
• bez mlijeka = without milk
• bez novca = without money

So bez + genitive is something worth memorizing.

Yes, in standard Croatian, bez takes the genitive.

Examples:

• bez šećera = without sugar
• bez soli = without salt
• bez tebe = without you
• bez problema = without a problem / no problem

If you learn bez together with the genitive, you will avoid a lot of mistakes.

Because Croatian does not have articles like English a/an and the.

So:

• kava can mean coffee, a coffee, or the coffee, depending on context.

In this sentence, ova already makes the meaning specific:

• ova kava = this coffee

That replaces the need for something like this coffee or the coffee here.

Yes. That is a correct sentence.

• Ova kava je gorka bez šećera. = This coffee is bitter without sugar.
• Kava je gorka bez šećera. = Coffee is bitter without sugar / The coffee is bitter without sugar.

The version with ova points to a specific coffee. Without ova, the sentence is more general or depends more on context.

Yes. Croatian word order is more flexible than English, because case endings and agreement already show the relationships between words.

The most neutral order here is:

• Ova kava je gorka bez šećera.

But other orders are possible for emphasis, for example:

• Bez šećera je ova kava gorka.
  This emphasizes without sugar.

Still, the original sentence is the most natural basic version for a learner.

Usually it means bitter, especially in taste, but like English bitter, it can also be used more figuratively in some contexts.

In this sentence, it clearly refers to taste:

• gorka kava = bitter coffee

You may also see related forms:

• gorak okus = bitter taste
• gorka čokolada = dark/bitter chocolate

So the exact form changes depending on the noun it describes.

There are patterns, but not every noun’s gender can be guessed with 100% certainty.

In this case, kava is feminine, and one clue is that many feminine nouns in Croatian end in -a in the nominative singular.

Examples:

• kava = coffee
• voda = water
• škola = school

Because kava is feminine, words that go with it must also be feminine:

• ova kava
• gorka kava

A rough English-friendly pronunciation is:

• še ≈ she
• će has a softer ch/t sound that English does not match exactly
• ra as written

So šećera is approximately SHE-che-ra, but with a softer sound in the middle than standard English ch.

Also:

• š sounds like sh
• ć is a soft Croatian consonant, somewhat between English t and ch

If you are just starting, pronouncing š as sh and ć as a soft ch is a good practical approximation.

In standard Croatian, kava is the normal word.

• kava = standard Croatian
• kafa = common in some other South Slavic varieties, but not standard Croatian

So if you are learning Croatian specifically, kava is the form to use.