Imala sam dobar san.

Imala sam means I had.

It is the Serbian past tense, built from:

• imala = the past participle of imati (to have), feminine singular
• sam = the short form of to be used with I

So Serbian past tense often works like:

• imala sam = I had
• imao sam = I had (said by a man)

Because the speaker is feminine.

In Serbian, the past participle agrees with the gender of the speaker:

• imala sam = said by a woman
• imao sam = said by a man

This is very common in Serbian past tense, so you often learn the speaker’s gender from the verb form.

Because Serbian usually leaves subject pronouns out when they are already clear from the verb.

So:

• Imala sam dobar san. = I had a good dream / sleep.
• Ja sam imala dobar san. = also correct, but ja adds emphasis, contrast, or clarity

English needs I, but Serbian often does not.

Because sam is a clitic, and clitics usually cannot stand at the very beginning of the sentence.

So without ja, Serbian naturally puts the participle first:

• Imala sam dobar san.

If you include the pronoun, then you get:

• Ja sam imala dobar san.

Both are correct, but sam imala... cannot normally start a sentence by itself.

Because dobar has to agree with san.

San is:

• masculine
• singular
• here used as a direct object

Since san is a masculine inanimate noun, the accusative singular looks the same as the nominative singular. So the adjective also keeps the form dobar:

• dobar san

Compare:

• dobar čovek = a good man
• dobrog čoveka = a good man (accusative, animate)

But with san (inanimate), it stays dobar san.

It is in the accusative case, because it is the direct object of imala sam.

The speaker had something — that thing is dobar san.

For masculine inanimate nouns in Serbian, the accusative singular is often identical to the nominative singular, which is why san does not change form here.

Because Serbian has no articles like English a and the.

So dobar san can mean:

• a good dream
• sometimes the good dream

The exact meaning depends on context, not on an article.

This is one of the big differences between English and Serbian.

San most commonly means dream, but in some contexts it can also refer to sleep.

So depending on the meaning already given to you, this sentence may be understood as:

• I had a good dream
• or more loosely I had good sleep

In everyday Serbian, if you specifically want to say I slept well, a very common phrase is:

• Dobro sam spavala. (woman)
• Dobro sam spavao. (man)

So Imala sam dobar san is understandable, but the most natural English translation depends on the context.