Završila sam rad.

Because the verb form agrees with the speaker’s gender in the past tense.

In Serbian, the past tense uses a special participle that changes for gender and number:

• završio sam = I finished (male speaker)
• završila sam = I finished (female speaker)

So Završila sam rad. is what a female speaker says.

sam is the 1st person singular present tense of biti (to be), and it helps form the Serbian past tense.

So the structure is:

• završila = past participle
• sam = auxiliary am

Together, they mean I finished / I have finished.

This is the normal way Serbian forms the past tense.

Because sam is a clitic. Clitics are short unstressed words that usually go in the second position of the sentence or clause.

So in:

• Završila sam rad.

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

You would not normally say:

• Sam završila rad. ❌

But you can say:

• Ja sam završila rad.
• Rad sam završila.

In both cases, sam still appears in the second position.

Yes. That is completely correct.

• Završila sam rad. = neutral, natural
• Ja sam završila rad. = I finished the work (with a bit more emphasis on I)

Serbian often leaves out subject pronouns like ja because the verb already shows the person. So adding ja is usually for emphasis, contrast, or clarity.

The dictionary form is završiti, which means to finish / to complete.

Here are some related forms:

• završiti = infinitive
• završim = I finish / I will finish
• završila sam = I finished (female)
• završio sam = I finished (male)

So završila is not the base form; it is a past participle form used in the past tense.

It is in the accusative case, but for many masculine inanimate nouns, the accusative looks exactly like the nominative.

So:

• rad = nominative
• rad = accusative

That is why the form does not visibly change.

This is normal for masculine inanimate nouns in Serbian.

rad can mean different things depending on context, such as:

• work
• piece of work
• assignment
• paper
• essay
• project

So Završila sam rad. could mean things like:

• I finished the assignment.
• I finished the paper.
• I finished the work.

The exact English translation depends on the situation.

Because Serbian does not have articles like a/an/the.

So rad can mean:

• a paper
• the paper
• work
• the work

Context tells you which meaning is intended.

This is a very common adjustment for English speakers learning Serbian.

završiti is a perfective verb.

That means it presents the action as completed. In this sentence, the idea is that the work is now finished.

So:

• Završila sam rad. = I finished the work / I completed the paper

The imperfective partner is usually završavati, which is used for ongoing, repeated, or process-focused actions.

For example:

• Završavala sam rad. = I was finishing the paper / I used to be finishing it

In your sentence, the perfective verb makes sense because the action is complete.

Not usually in the broad sense of I finished work for the day.

Završila sam rad more naturally suggests that you finished a specific piece of work, such as an assignment, report, or paper.

If you want to say I finished work in the sense of being done with your job or workday, Serbian often uses something like:

• Završila sam posao.
• Završila sam s poslom.

So rad and posao can overlap, but they are not always used in exactly the same way.

Yes, Serbian word order is fairly flexible, but the meaning and emphasis can shift.

For example:

• Završila sam rad. = neutral
• Rad sam završila. = emphasizes the work
• Ja sam završila rad. = emphasizes I

The main thing to remember is that the clitic sam usually stays in the second position.

A male speaker would say:

• Završio sam rad.

The only change is the participle:

• završila = female speaker
• završio = male speaker

Everything else stays the same.

Yes, there can be a nuance difference.

• Završila sam rad focuses on finishing/completing the work.
• Uradila sam rad focuses more on doing the work, though it can also imply completion.

In many contexts, both are possible, but završila sam rad strongly highlights that the task is now complete. For something like a paper, project, or assignment, this is very natural.