Stavi čep natrag na bocu i zatvori pretinac, molim te.

They are imperative forms, used for giving a command or instruction.

• stavi = put
• zatvori = close

More specifically, these are the 2nd person singular informal imperative forms, so the speaker is talking to one person in a familiar way.

Base verbs:

• staviti → stavi
• zatvoriti → zatvori

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

• Stavite čep natrag na bocu i zatvorite pretinac, molim Vas.

Croatian usually does not need subject pronouns when the verb already shows who is being addressed.

So:

• Stavi... already means you put...
• Zatvori... already means you close...

The pronoun ti can be added, but only for emphasis or contrast:

• Ti stavi čep, a ja ću zatvoriti pretinac.
  = You put the cap on, and I’ll close the compartment.

In normal instructions, leaving out ti is completely natural.

Because čep is the direct object, and for many inanimate masculine nouns, the accusative singular looks exactly the same as the nominative singular.

So:

• nominative: čep
• accusative: čep

That is why after stavi you still see čep.

Compare this with an animate masculine noun, where the accusative changes:

• pas = dog
• Vidim psa. = I see the dog.

But:

• čep = cap
• Stavi čep. = Put the cap.

Because na can take different cases depending on the meaning.

Here, the sentence expresses movement toward a destination: putting the cap onto the bottle. With movement like that, na takes the accusative.

• na bocu = onto the bottle

If you were talking about location, not movement, you would use the locative:

• Čep je na boci. = The cap is on the bottle.

So the contrast is:

• stavi čep na bocu = movement → accusative
• čep je na boci = location → locative

Natrag means back.

So:

• Stavi čep natrag na bocu = Put the cap back on the bottle

It shows that the cap had been on the bottle before, was removed, and should now be returned.

A very similar word is nazad, which can also mean back. In many situations, natrag and nazad are interchangeable, though natrag often sounds a bit more standard in careful usage.

This is about aspect, which is very important in Croatian.

• staviti and zatvoriti are perfective
• stavljati and zatvarati are imperfective

Here the speaker wants a single completed action:

• put the cap back on
• close the compartment

That is why the perfective imperative is natural:

• stavi
• zatvori

If you used the imperfective imperative, it would sound more like repeated, ongoing, or process-focused action, depending on context.

So in simple one-time instructions, perfective verbs are usually the right choice.

Pretinac is a general word for a compartment, section, drawer, or storage space, depending on context.

It can refer to things like:

• a drawer in furniture
• a compartment in a bag or case
• a glove compartment in a car
• a small divided section inside something

So the exact English translation depends on the situation. Croatian uses pretinac quite broadly.

Molim te is the normal informal way to say please when speaking to one person.

• molim = literally related to I ask / I beg
• te = you (object form)

But as a fixed expression, molim te simply works like please.

It is polite, but informal. If you need to be formal, use:

• molim Vas

So:

• ..., molim te. = informal please
• ..., molim Vas. = formal please

Because molim te is being used as a parenthetical politeness expression, similar to English please in some sentence positions.

So the comma separates it from the main instruction:

• Stavi čep natrag na bocu i zatvori pretinac, molim te.

You can also place molim te in other positions:

• Molim te, stavi čep natrag na bocu i zatvori pretinac.
• Stavi, molim te, čep natrag na bocu i zatvori pretinac.

All are possible, though some sound more natural than others depending on tone and emphasis.

No, Croatian word order is fairly flexible, but the given order is natural and clear.

The sentence:

• Stavi čep natrag na bocu i zatvori pretinac, molim te.

sounds like a normal instruction.

You may also hear variations such as:

• Stavi natrag čep na bocu...
• Čep stavi natrag na bocu...

But these can change the emphasis slightly, and some versions may sound less neutral.

For learners, the original order is a very good model to follow.

Yes. That is a very natural alternative.

• stavi čep natrag na bocu = put the cap back on the bottle
• vrati čep na bocu = return the cap to the bottle / put the cap back on the bottle

The verb vratiti often naturally includes the idea of putting something back. So in some contexts, vrati čep na bocu may sound even more compact or idiomatic.

Still, the original sentence is absolutely correct and clear.