Raspakovala sam porudžbinu.

Because Serbian often drops subject pronouns when they are already clear from the verb form and context.

In Raspakovala sam porudžbinu, the combination of sam and raspakovala already tells you this means I unpacked.

You can say Ja sam raspakovala porudžbinu, but adding ja usually gives extra emphasis, like I unpacked it.

Sam is a clitic in Serbian, meaning it is an unstressed word that normally goes in the second position of the sentence or clause.

So in:

Raspakovala sam porudžbinu

the first element is Raspakovala, and the clitic sam comes right after it.

Other possible word orders are:

• Ja sam raspakovala porudžbinu.
• Porudžbinu sam raspakovala.

But sam still stays near the beginning, in that second-position slot.

This is the Serbian past tense, formed with:

• the l-participle of the main verb
• plus the present tense of biti as an auxiliary

Here:

• raspakovala = the participle
• sam = I am, used here as the auxiliary for the past tense

So literally, the structure is something like unpacked am, but it simply means I unpacked.

Because the participle agrees with the gender of the speaker.

• raspakovala sam = I unpacked said by a female
• raspakovao sam = I unpacked said by a male

So this sentence tells you the speaker is female.

It comes from the verb raspakovati, which means to unpack.

A useful comparison is:

• pakovati = to pack
• raspakovati = to unpack

The prefix ras- often gives a sense of undoing, spreading apart, or taking out what was packed.

Yes. Raspakovati is a perfective verb, so it presents the action as completed.

So Raspakovala sam porudžbinu means the unpacking is viewed as a finished whole.

If you wanted an ongoing or repeated meaning, you would normally use an imperfective verb, for example:

• Raspakivala sam porudžbinu.

That could mean I was unpacking the order or I used to unpack the order, depending on context.

Because porudžbinu is in the accusative singular.

Porudžbina is the nominative form, the dictionary form. But here it is the direct object of the verb raspakovala, so it changes case:

• porudžbina = nominative
• porudžbinu = accusative

This is a very common pattern for feminine nouns ending in -a:

• knjiga → knjigu
• torba → torbu
• porudžbina → porudžbinu

Yes, Serbian word order is fairly flexible because case endings show grammatical roles.

These are all possible, with different emphasis:

• Raspakovala sam porudžbinu. = neutral
• Ja sam raspakovala porudžbinu. = emphasis on I
• Porudžbinu sam raspakovala. = emphasis on the order

The main thing to remember is that the clitic sam still follows the first element.

A man would say:

Raspakovao sam porudžbinu.

The only change is the participle:

• raspakovala = feminine singular
• raspakovao = masculine singular

Everything else stays the same.

No. Depending on region and style, you may also see words like narudžbina, porudžba, or narudžba.

In Serbian, porudžbina and narudžbina are both understandable, though preferences can vary by speaker and region.

So the grammar of this sentence stays the same even if the noun changes:

• Raspakovala sam porudžbinu.
• Raspakovala sam narudžbinu.

Both are structurally normal.