Skinut ću navlaku s jastuka i staviti čistu.

Because in Croatian future tense, when an infinitive ending in -ti comes directly before the auxiliary ću, the final -i is usually dropped.

So:

• skinuti → skinut ću
• raditi → radit ću
• pisati → pisat ću

But if the auxiliary comes first, the full infinitive stays:

• Ja ću skinuti navlaku...

Both patterns are normal.

Because only the infinitive that stands directly before ću loses its final -i.

Here ću is attached to the first verb:

• Skinut ću

Then the second verb is just another infinitive coordinated with the first:

• ... i staviti čistu

So staviti keeps its full form.

Croatian often leaves out subject pronouns when they are already clear from the verb form.

Here ću tells you the speaker is first person singular, so I will is already built in.

You could add ja for emphasis:

• Ja ću skinuti navlaku s jastuka i staviti čistu.

But it is not necessary.

Navlaku is accusative singular of navlaka.

It is in the accusative because it is the direct object of the verbs skinuti and understood again with staviti.

• nominative: navlaka
• accusative: navlaku

So the sentence is talking about doing something to the cover: removing it and replacing it.

Here s means from/off, and with that meaning it takes the genitive case.

So:

• jastuk = pillow
• jastuka = genitive singular

s jastuka means off the pillow or from the pillow.

This is different from s + instrumental, which means with:

• s jastukom = with the pillow

So case depends on meaning.

Because the noun is omitted, but it is still understood from context.

Čistu really means:

• čistu navlaku

Croatian often does this when the noun has already been mentioned or is obvious. English often uses one in the same situation:

• put a clean one on

Croatian usually just uses the adjective by itself.

Because the omitted noun is navlaku, which is:

• feminine
• singular
• accusative

The adjective has to match that omitted noun, so:

• nominative feminine singular: čista
• accusative feminine singular: čistu

So čistu agrees with the understood navlaku.

Because repeating it is not necessary.

Croatian often avoids repeating words that are already clear:

• Skinut ću navlaku s jastuka i staviti čistu.

The full version would be something like:

• Skinut ću navlaku s jastuka i staviti čistu navlaku.

But that sounds more repetitive. The shorter version is natural.

Because it is understood from context.

After skinut ću navlaku s jastuka, it is obvious that the speaker means they will put a clean cover back onto the same pillow.

Croatian often leaves out information that is obvious, especially in everyday speech.

Because skinuti and staviti are perfective verbs. They describe single, completed actions:

• remove the cover
• put on a clean one

That matches the meaning of this sentence very well.

The imperfective verbs skidati and stavljati would suggest repeated, ongoing, or habitual action, depending on context.

So this sentence focuses on a complete future action, not on the process.

Yes. That is also correct.

Compared with the original:

• Skinut ću navlaku s jastuka i staviti čistu.

the version with ja ću is a little more explicit and may feel easier to understand for learners.

Croatian word order is fairly flexible, so both are natural, with slightly different rhythm and emphasis.

Navlaka literally means cover or covering, so it is a general word.

In this sentence, because of s jastuka, it clearly means the pillow’s cover, so the meaning is easy to understand.

A more specific word for pillowcase is jastučnica. So in some contexts you might also hear:

• Skinut ću jastučnicu i staviti čistu.

But navlaka works fine when the context already makes the object clear.