U hodniku je mrak, pa ću upaliti svjetlo.

Because u can take different cases depending on the meaning:

• u + accusative = motion into somewhere
  
  • Idem u hodnik. = I’m going into the hallway.
• u + locative = location in somewhere
  
  • U hodniku je mrak. = It’s dark in the hallway.

Here, the sentence describes where the darkness is, so Croatian uses the locative: hodnik → hodniku.

It is the locative singular of hodnik (hallway, corridor).

Many masculine nouns in the locative singular end in -u:

• grad → u gradu
• stan → u stanu
• hodnik → u hodniku

After u meaning in/at, the locative is very common.

Croatian often uses the noun mrak (darkness) in this pattern:

• Je mrak. = It’s dark.
• literally: There is darkness.

This is a very natural Croatian way to express darkness. You can also hear:

• Mračno je. = It’s dark.

Both are correct, but U hodniku je mrak is completely normal and idiomatic.

Because Croatian has no articles. There is no direct equivalent of English a/an or the.

So:

• hodnik can mean a hallway or the hallway
• svjetlo can mean a light or the light

The exact meaning depends on context. In this sentence, upaliti svjetlo naturally means turn on the light.

Here pa means something like:

• so
• and so
• therefore
• sometimes just a natural linking word: so then

In this sentence:

• U hodniku je mrak, pa ću upaliti svjetlo.
• It’s dark in the hallway, so I’ll turn on the light.

It connects the first idea to its consequence. It is very common in everyday Croatian and often sounds more natural in speech than a heavier connector like zato or stoga.

Both are correct, but the version in your sentence follows a very common Croatian pattern.

ću is a clitic form of htjeti used to make the future tense. Clitics usually go in the second position in the clause.

So Croatian often says:

• pa ću upaliti svjetlo

You can also say:

• upalit ću svjetlo

That version is also natural. In modern standard Croatian, both patterns are used:

• ću + infinitive
• short infinitive + ću

But after a connector like pa, pa ću upaliti... is especially common and smooth.

It is the future tense (futur I).

It is formed with:

• a present-tense clitic of htjeti (to want, but here functioning as a future auxiliary)
• plus the infinitive of the main verb

So:

• ću = I will
• upaliti = turn on / switch on

Together:

• ću upaliti = I will turn on

The full set is:

• ja ću
• ti ćeš
• on/ona/ono će
• mi ćemo
• vi ćete
• oni/one/ona će

Because upaliti is the perfective verb, and Croatian usually uses a perfective verb for a single completed future action.

• paliti = imperfective, to be turning on / to turn on habitually
• upaliti = perfective, to turn on once, successfully

In this sentence, the speaker means one specific action:

• I’ll turn on the light.

So upaliti is the natural choice.

Here svjetlo is the direct object of upaliti, so it is in the accusative case.

However, svjetlo is a neuter noun, and in the singular its nominative and accusative forms are the same:

• nominative: svjetlo
• accusative: svjetlo

So even though the form does not change, its grammatical role does: here it is the object of the verb.

In modern everyday Croatian, upaliti svjetlo normally means turn on the light.

Historically, upaliti is related to ignite/set on fire, but in ordinary speech it is the standard verb for switching on lights and other devices.

Examples:

• Upali svjetlo. = Turn on the light.
• Upali televizor. = Turn on the TV.
• Upali auto. = Start the car.

So in this sentence, the natural translation is definitely turn on the light.

Yes. That is also correct and natural.

Compare:

• U hodniku je mrak. = It’s dark in the hallway.
  Slightly more concrete, literally there is darkness.
• U hodniku je tamno. = It’s dark in the hallway.
  Uses the adverb/adjectival form tamno.

Both are common. The version with mrak sounds very idiomatic and everyday.

Not completely. Croatian word order is fairly flexible, but not random. The original sentence is very natural:

• U hodniku je mrak, pa ću upaliti svjetlo.

You may also hear variations depending on emphasis:

• Mrak je u hodniku, pa ću upaliti svjetlo.
  This puts more focus on mrak.
• Svjetlo ću upaliti, jer je u hodniku mrak.
  This emphasizes svjetlo.

Still, the original version is the most neutral and natural for everyday use.

ću is pronounced roughly like chyoo, but very short and compact.

A few notes:

• ć is a soft Croatian sound, somewhat like a very soft ch
• u is like oo in food

So ću is approximately chyoo, though English does not have the exact ć sound.

If you want a practical learner tip:

• ću is softer than ču
• ć is usually softer and more “compressed” than č

Yes, svjetlo can be tricky for English speakers.

It is roughly pronounced SVYET-lo.

Break it down like this:

• svje ≈ svye
• tlo ≈ tlo

The cluster svj is normal in Croatian, even though it feels heavy in English. Try not to insert extra vowels. Not suh-vyet-lo, but one compact word: svjetlo.

A slow practice version:

• svje-tlo
• then faster: svjetlo