Juče sam rano čekala autobus na stanici.

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

In sam čekala, sam tells you it is first person singular, so I is understood. The ending in čekala also shows that the speaker is female.

You could say Ja sam rano čekala autobus na stanici, but ja is usually unnecessary unless you want extra emphasis.

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

So in Juče sam rano čekala autobus na stanici, the first element is Juče, and sam comes right after it.

This is very natural Serbian word order. English speakers often expect sam to stay next to the main verb, but Serbian does not work that way.

The Serbian past tense is commonly formed with:

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

Here:

• sam = first person singular auxiliary
• čekala = past participle of čekati

So sam čekala means I waited or I was waiting, depending on context.

Because the past participle agrees with the gender of the speaker.

• čekala = feminine singular
• čekao = masculine singular

So this sentence was said by a woman or girl. If a man were speaking, it would be Juče sam rano čekao autobus na stanici.

Because Serbian uses čekati with a direct object, while English usually says wait for something.

So:

• English: wait for the bus
• Serbian: čekati autobus

That is a very common difference between the two languages.

It is in the accusative case because it is the direct object of čekati.

The tricky part is that many masculine inanimate nouns have the same form in nominative and accusative singular. So:

• nominative: autobus
• accusative: autobus

Even though the form looks unchanged, the case is still accusative here.

After na, Serbian can use different cases depending on the meaning.

Here it expresses location, so na takes the locative:

• stanica = station / stop
• na stanici = at the station / at the stop

If there were movement toward it, Serbian might use a different case instead.

Rano is an adverb meaning early.

It modifies the action čekala, so it tells you that the waiting happened early. In context, that often means early in the day or earlier than expected.

It does not mean quickly.

It can mean either, depending on context.

The verb čekati is imperfective, so it often describes an ongoing, repeated, or uncompleted action. Because of that, English may translate it as:

• I waited
• I was waiting

In this sentence, I was waiting often feels especially natural in English, but I waited is also possible depending on the broader situation.

Yes, Serbian word order is flexible, but the emphasis changes.

For example:

• Juče sam rano čekala autobus na stanici = neutral, with focus starting from yesterday
• Rano sam juče čekala autobus na stanici = stronger focus on early
• Autobus sam juče rano čekala na stanici = stronger focus on the bus

What usually stays important is the clitic rule: sam still tends to appear in second position.

Serbian does not have articles.

So autobus can mean a bus or the bus, and stanici can mean a station/stop or the station/stop. The exact meaning comes from context.

That is why one Serbian sentence can match several natural English versions.

It can mean either, depending on context.

In autobus na stanici, it often means bus stop or sometimes bus station, depending on the situation. Serbian often relies on context more than English here.

So na stanici is not always one fixed English word-for-word translation.