Ne znam je li moja narudžba već poslana.

Here je li introduces an indirect yes/no question, so it means whether / if.

• Ne znam = I don’t know
• je li moja narudžba već poslana = whether my order has already been sent

So the structure is literally: I don’t know whether my order is already sent / has been sent.

In standard Croatian, it is written as two words: je li.

• je is the 3rd person singular form of biti (to be)
• li is a particle used to form yes/no questions

So:

• Je li moja narudžba već poslana? = Has my order already been sent?

Writing jeli as one word is a very common mistake in informal writing, but it is not standard.

Because it agrees with narudžba, which is a feminine singular noun.

The passive participle changes to match the noun in gender and number:

• masculine: poslan
• feminine: poslana
• neuter: poslano

Since moja narudžba is feminine singular, Croatian uses poslana.

Yes. This is a passive construction.

The verb behind it is poslati = to send.
Its passive participle is:

• poslan / poslana / poslano

So moja narudžba je poslana literally means my order is sent, but in natural English it is often my order has been sent.

Croatian does not build this idea the same way English does.

English says:

• has been sent

Croatian uses:

• je poslana

That is often enough to express the result of a completed action, especially with a perfective verb like poslati and with već (already). So Croatian je poslana can naturally correspond to English has been sent.

Literally, već means already.

So:

• Je li moja narudžba već poslana? can literally be Has my order already been sent?

But in natural English, depending on context, you might also translate it as:

• Has my order been sent yet?
• I don’t know if my order has been sent yet.

So Croatian uses već, while English may choose already or yet depending on what sounds most natural.

Because it is the subject of the subordinate clause:

• je li moja narudžba već poslana

The thing that is being sent is moja narudžba, so it stays in the nominative:

• moja narudžba = nominative feminine singular

Also, moja matches narudžba in gender, number, and case.

Yes, if the context already makes it clear whose order you mean.

• Ne znam je li narudžba već poslana. = I don’t know if the order has already been sent.

Adding moja makes it explicit: my order. Croatian often omits possessives when they are obvious, but keeping moja is completely natural.

Yes, Croatian word order is fairly flexible, though the original version is the most neutral:

• Ne znam je li moja narudžba već poslana.

You may also hear variations such as:

• Ne znam je li već poslana moja narudžba.

That version is possible, but it sounds a bit more marked and may shift emphasis. The original sentence is the safest and most natural choice for a learner.

Not exactly. If you use da li, you still need the verb je:

• Ne znam da li je moja narudžba već poslana.

In everyday speech, many speakers use da li, but in standard Croatian, especially in writing, je li is usually preferred here:

• Ne znam je li moja narudžba već poslana.

So for a learner, je li is the best version to remember.

Because this je li clause functions as the object of ne znam:

• Ne znam [je li moja narudžba već poslana].

In Croatian, tightly connected object clauses like this are normally written without a comma.

So this is correct:

• Ne znam je li moja narudžba već poslana.

The infinitive is poslati = to send.

This verb is perfective, which means it naturally refers to a completed action. That is why the sentence gives the sense of:

• has been sent
• already sent

Its imperfective partner is slati = to be sending / to send repeatedly. In this sentence, the perfective verb is the right choice because the speaker is wondering whether the sending has been completed.