Ako želiš upaliti svjetlo, stisni ovu tipku.

In Croatian, after verbs like željeti (to want), you usually put the infinitive directly:

• želim jesti = I want to eat
• želiš upaliti = you want to turn on

So upaliti already means to turn on. Croatian does not need a separate word like English to here.

Želiš is the 2nd person singular present tense of željeti (to want).

The subject is understood from the verb ending:

• želim = I want
• želiš = you want
• želi = he/she/it wants

So Ako želiš... means If you want.... Croatian often leaves out the subject pronoun ti (you) because the verb ending already shows who the subject is.

Upaliti is the perfective infinitive, meaning a single completed action: to switch on / to turn on.

That fits this sentence well, because the idea is one specific action: turning the light on.

Compare:

• upaliti = to turn on, once, successfully
• upaljivati = to be turning on repeatedly / habitually / in general

And upališ would be a finite verb form (you turn on), not an infinitive. After želiš, Croatian normally uses the infinitive:

• želiš upaliti = correct
• želiš upališ = not correct standard grammar

Svjetlo is a neuter noun. In this sentence it is the direct object of upaliti.

For many neuter nouns in Croatian, the nominative and accusative singular look the same. So:

• nominative: svjetlo = the light
• accusative: svjetlo = the light

That is why the form does not change here.

Stisni is the imperative singular of stisnuti (to press, to squeeze).

This is the form used when giving a direct instruction to one person:

• stisni = press!
• reci = say!
• dođi = come!

So the sentence is telling one person what to do.

If you were speaking politely or to more than one person, you would usually say:

• stisnite ovu tipku = press this button

Because tipku is the direct object of stisni, it has to be in the accusative case.

The noun tipka is feminine, so:

• nominative: ova tipka = this button
• accusative: ovu tipku = this button

Both the adjective/demonstrative and the noun change:

• ova → ovu
• tipka → tipku

This is a very common pattern with feminine nouns in -a.

Yes, here tipka means button or key, depending on context.

Common uses:

• tipka on a keyboard = key
• tipka on a machine or device = button

In this sentence, ovu tipku is naturally understood as this button.

You may also hear dugme in some varieties of the language, but tipka is very common and standard.

The first part, Ako želiš upaliti svjetlo, is a subordinate if-clause. In Croatian, when a subordinate clause comes before the main clause, it is normally separated by a comma.

So:

• Ako želiš upaliti svjetlo, stisni ovu tipku.

This works like English punctuation in many similar sentences.

Yes, Croatian word order is fairly flexible, though some orders sound more natural than others.

The original sentence is very natural:

• Ako želiš upaliti svjetlo, stisni ovu tipku.

You could also reverse the clauses:

• Stisni ovu tipku ako želiš upaliti svjetlo.

That still means the same thing.

However, inside the smaller phrases, the original order is the most neutral and natural for learners to use.

Yes. Pritisni ovu tipku is also natural and often very common for press this button.

Roughly speaking:

• stisnuti = to press / squeeze
• pritisnuti = to press

In many everyday contexts, both work. Device instructions often use pritisnuti or stisnuti, depending on region and style.

A rough pronunciation guide is:

• svjetlo ≈ svyet-lo
• želiš ≈ zhe-lish
• stisni ≈ stees-nee
• tipku ≈ teep-koo

A few useful points:

• j in Croatian is pronounced like English y in yes
• ž sounds like the s in measure
• š sounds like English sh

So svjetlo starts with a cluster that may feel difficult at first: svj-. Saying it slowly as sv-ye-tlo can help.