Kuhar u restoranu danas pravi juhu od gljiva.

Because juhu is in the accusative singular.

The verb praviti / praviti here means to make / prepare, and juha is the direct object of the verb, so it must go into the accusative:

• juha = nominative, the basic dictionary form
• juhu = accusative, used for the object

So:

• Juha je dobra. = The soup is good.
• Pravi juhu. = He/She is making soup.

This is very common in Croatian: the object changes form depending on case.

Because after u meaning in, Croatian normally uses the locative case.

• restoran = basic form (nominative)
• u restoranu = in the restaurant (locative)

So:

• restoran = restaurant
• u restoranu = in the restaurant

A useful contrast:

• u restoranu = in the restaurant → location
• u restoran = would suggest motion into the restaurant, but in standard Croatian that is normally u restoran / u restoran? Actually with motion, the correct form is u restoran only in some very limited patterns; with this noun, standard usage is still u restoran as accusative only if the noun’s accusative matches nominative, which it does here. So:
  • On je u restoranu. = He is in the restaurant.
  • Ide u restoran. = He is going into/to the restaurant.

In your sentence, it is clearly location, so u restoranu is required.

After the preposition od, Croatian uses the genitive.

So gljiva here is the genitive plural of gljive (mushrooms):

• gljiva = mushroom / also a form used in other case contexts
• gljive = mushrooms (nominative plural)
• od gljiva = of/from mushrooms

In food expressions, od + genitive often means made from or with:

• juha od gljiva = mushroom soup
• sok od naranče = orange juice
• pire od krumpira = mashed potatoes / potato purée

So juhu od gljiva literally means soup made from mushrooms.

Yes, absolutely.

Both are natural, but there is a slight difference in feel:

• pravi juhu = is making/preparing soup
• kuha juhu = is cooking soup

So:

• pravi focuses a bit more on preparing the dish
• kuha focuses more specifically on cooking

In everyday speech, both can work well here.

Because the subject is kuhar = the cook / chef, which is third person singular.

The verb must agree with the subject:

• ja pravim = I make
• ti praviš = you make
• on/ona pravi = he/she makes
• mi pravimo = we make
• vi pravite = you make
• oni/one prave = they make

Since kuhar is he / the cook, the correct form is pravi.

Usually, yes in many contexts, though kuhar most literally means cook.

Depending on context, English may translate it as:

• cook
• chef

If you want a female cook/chef, the usual form is:

• kuharica

So:

• Kuhar pravi juhu. = The cook/chef is making soup.
• Kuharica pravi juhu. = The female cook/chef is making soup.

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

So kuhar can mean:

• a cook
• the cook

and juhu can mean:

• a soup
• the soup

The exact meaning depends on context.

That is why one Croatian sentence can correspond to several English versions, such as:

• The cook in the restaurant is making mushroom soup today.
• A cook in the restaurant is making a mushroom soup today.

English must choose an article, but Croatian usually does not.

Yes. Croatian word order is more flexible than English word order because case endings show the grammatical roles.

Your sentence is:

• Kuhar u restoranu danas pravi juhu od gljiva.

But you could also hear:

• Danas kuhar u restoranu pravi juhu od gljiva.
• Kuhar danas u restoranu pravi juhu od gljiva.
• Juhu od gljiva danas pravi kuhar u restoranu.

These versions all keep basically the same core meaning, but the focus changes:

• putting danas early emphasizes today
• putting juhu od gljiva early emphasizes the soup
• putting kuhar early feels neutral and straightforward

So Croatian word order often expresses emphasis rather than strict grammar alone.

Danas means today, and it is fairly mobile.

You can place it in different positions depending on what you want to emphasize:

• Kuhar danas pravi juhu od gljiva.
• Danas kuhar pravi juhu od gljiva.
• Kuhar pravi danas juhu od gljiva.
• Kuhar pravi juhu od gljiva danas.

Some positions sound more natural than others depending on style and context, but all are understandable.

In your original sentence, danas sits in a very natural middle position.

In this sentence:

• kuhar = singular
• restoranu = singular
• juhu = singular
• gljiva = plural here, because it is genitive plural after od

This last one can confuse learners because gljiva can look like a singular form, but in od gljiva, it means of mushrooms, not of a mushroom.

So the phrase:

• juha od gljiva

means:

• mushroom soup
• literally soup of mushrooms

It can be understood as describing the setting of the action, and in practice that usually also tells you where the cook is.

So the sentence naturally means:

• The cook is making mushroom soup in the restaurant today.

You do not need to force a strict distinction here. In normal use, u restoranu gives the location for the whole situation.

Here are the basic forms:

• kuhar → kuhar
• u → u
• restoranu → restoran
• danas → danas
• pravi → praviti or in some dictionaries praviti / pravim
• juhu → juha
• od → od
• gljiva → gljiva (singular dictionary form), though here the meaning is plural because the form is genitive plural

This is useful because Croatian learners often need to recognize that the word in the sentence is not always the dictionary form.