Pitala sam ljekarnicu može li mi ostaviti isti vitamin do sutra.

Because the past participle agrees with the speaker’s gender.

• pitala sam = I asked spoken by a woman
• pitao sam = I asked spoken by a man

So this sentence tells you the speaker is female.

It is the Croatian perfect tense (a common past tense).

It is built from:

• the past participle: pitala
• the auxiliary sam = am

So:

• pitala sam = I asked

Croatian usually uses this structure where English often just uses a simple past.

Because Croatian often drops subject pronouns when they are already clear from the verb form.

• sam already tells you the subject is I
• pitala also tells you the speaker is feminine

So (Ja) pitala sam... would be possible, but ja is usually unnecessary unless you want emphasis.

Because ljekarnicu is the accusative singular form, and it is the direct object of pitati.

• ljekarnica = female pharmacist, nominative
• ljekarnicu = female pharmacist, accusative

Since the speaker asked the pharmacist, Croatian uses the accusative after pitati nekoga = to ask someone.

No. It means the female pharmacist.

This is a very common point of confusion:

• ljekarna = pharmacy
• ljekarnik = male pharmacist
• ljekarnica = female pharmacist

So pitala sam ljekarnicu means I asked the female pharmacist, not I asked at the pharmacy.

Because li is used to form a yes/no question, including an indirect one.

Here the clause može li mi ostaviti isti vitamin do sutra means something like:

• if she can leave/hold the same vitamin for me until tomorrow
• whether she can...

In Croatian, li normally comes right after the finite verb:

• može li
• not normally li može

So this is the standard order.

Because Croatian often expresses this idea with verb + li instead of a separate word like English if/whether.

So:

• Pitala sam ljekarnicu može li... literally looks like
• I asked the pharmacist can-Q...

But naturally it means:

• I asked the pharmacist if/whether she could...

This is a very normal Croatian structure.

Because Croatian does not always shift tenses the way English does.

English often says:

• I asked if she could...

Croatian commonly says:

• pitala sam ... može li... literally I asked ... can she...

That present tense in Croatian is normal here. It refers to the possibility from the point of view of that past moment.

mi is the dative clitic meaning to me or for me.

So:

• ostaviti mi = leave for me / keep for me
• in more natural English here: hold for me, set aside for me

Croatian clitic pronouns are short unstressed forms, and mi is one of them.

Because Croatian has special rules for clitics like li and mi.

Here is the order:

• može = the finite verb
• li = question particle, placed right after the verb
• mi = clitic pronoun
• ostaviti = infinitive

So može li mi ostaviti is a very natural clitic sequence.

Croatian word order is flexible, but clitics are much less flexible than full words.

Yes, ostaviti literally often means to leave, but in this context it means something like:

• leave aside
• set aside
• keep
• hold
• reserve

So here the idea is not just physically leaving something somewhere. It means the pharmacist keeps that vitamin available for the speaker until tomorrow.

Because it follows the modal verb može.

After modal verbs like:

• moći = can / be able to
• morati = must
• htjeti = want

Croatian normally uses the infinitive of the main verb.

So:

• može ostaviti = can leave / can keep

isti means same.

So isti vitamin means:

• the same vitamin
• the same kind/brand/item as before, not a different one

The adjective isti agrees with vitamin in gender, number, and case.

Here:

• vitamin is masculine singular
• it is in the accusative
• because it is masculine inanimate, the accusative looks the same as the nominative

So:

• nominative: isti vitamin
• accusative: isti vitamin

No visible change happens here.

Because Croatian has no articles like English a/an/the.

So Croatian often expresses definiteness through context, word choice, or adjectives such as isti.

In English you would naturally say:

• the same vitamin

But Croatian simply says:

• isti vitamin

do sutra means until tomorrow or sometimes by tomorrow, depending on context.

In this sentence it means the pharmacist would keep the vitamin available up to tomorrow.

So the idea is:

• Can she hold it for me until tomorrow?

Yes, somewhat. Croatian word order is flexible, but the clitics still have to behave properly.

For example, you could also hear:

• Pitala sam ljekarnicu može li do sutra ostaviti mi isti vitamin.
  This is much less natural because mi should stay in the clitic position.

A much better alternative is:

• Pitala sam ljekarnicu može li mi do sutra ostaviti isti vitamin.

That still means the same thing, but now do sutra is moved for emphasis.

So the sentence can be rearranged a little, but li and mi need to stay in their normal clitic positions.

Yes. Depending on style and region, a speaker might use other verbs such as:

• sačuvati = keep, save
• ostaviti sa strane = put aside
• rezervirati = reserve

But ostaviti is very natural in everyday speech for set aside / hold for someone.