Juče sam kupila poklon, ali nisam našla cveće.

Serbian often leaves out subject pronouns when they are already clear from the verb form.

In sam kupila and nisam našla, the speaker is clearly I, so ja is not necessary.

You could say Ja sam kupila poklon, but that usually adds emphasis, like I bought the gift.

Those forms show that the speaker is feminine.

In the Serbian past tense, the main verb agrees with the subject in gender and number:

• kupila / našla = feminine singular
• kupio / našao = masculine singular
• kupilo / našlo = neuter singular
• kupili / našle etc. = plural

So this sentence was said by a woman. If a man said it, it would be:

Juče sam kupio poklon, ali nisam našao cveće.

The Serbian past tense here is made with:

• a form of biti = to be
• plus the past participle of the main verb

So:

• sam kupila = I bought
• nisam našla = I did not find

More literally:

• sam = am
• kupila = bought in the feminine form

This is the normal way to form the past tense in Serbian.

Because sam is a clitic, and Serbian clitics usually go in the second position of the clause.

So in Juče sam kupila poklon:

• Juče is the first element
• sam comes right after it

That is why Juče sam kupila sounds natural.

A learner may expect word order more like English, but Serbian clitics follow their own placement rules.

Because the negative form of sam is not written separately.

You do not say ne sam. Instead, Serbian uses fused negative forms of biti:

• nisam = I am not / I did not
• nisi = you are not / you did not
• nije = he/she/it is not / did not
• etc.

So:

• sam kupila = I bought
• nisam kupila = I did not buy

They are direct objects, so they are in the accusative case.

However, their forms do not visibly change here:

• poklon is masculine inanimate, and for masculine inanimate nouns, nominative and accusative singular are usually the same
• cveće is neuter singular, and neuter nominative and accusative singular are also the same

So even though both words are in the accusative, they look unchanged.

Because cveće is a collective noun in Serbian.

It often means flowers as a general mass or collection, even though grammatically it is singular/neuter.

So:

• našla sam cveće = I found flowers
• not necessarily just one flower

If you wanted to talk about individual flowers more explicitly, Serbian can use forms based on cvet, but cveće is very common when talking about flowers in a general sense, especially things like buying or finding flowers.

These are perfective verbs:

• kupiti = to buy, as a completed act
• naći = to find, as a completed result

That fits this sentence because it talks about completed events yesterday:

• the gift was bought
• the flowers were not found

If you used imperfective verbs, the meaning would shift toward process, repetition, or ongoing action rather than a single completed event.

That is a good question, because learners sometimes hear that negation can affect the object case.

In modern Serbian, the direct object after negation is very often still in the accusative, especially in everyday language:

• Nisam našla cveće.

That is completely normal.

You may sometimes encounter genitive after negation in certain styles or contexts, but for this sentence, the accusative is standard and natural.

Because Serbian has no articles.

English distinguishes:

• a gift
• the gift

Serbian usually does not mark that difference with a separate word. So poklon can mean:

• a gift
• the gift

The exact meaning depends on context.

Ali means but.

It connects two clauses and shows contrast:

• Juče sam kupila poklon = Yesterday I bought a gift
• ali nisam našla cveće = but I didn’t find flowers

So it works very much like English but.