Jutros sam bila pospana, pa sam zaboravila kišobran.

Because there are really two separate verb phrases in the sentence:

• sam bila pospana = I was sleepy
• sam zaboravila kišobran = I forgot the umbrella

In Croatian, the auxiliary sam is used to form both:

• the past tense: sam zaboravila
• the past form of to be with an adjective: sam bila pospana

So each clause needs its own sam.

Those forms show that the speaker is female.

In Croatian, some past-tense forms and adjectives agree with the speaker’s gender:

• bila = feminine singular of bio / bila / bilo
• pospana = feminine singular adjective
• zaboravila = feminine singular past participle

A male speaker would say:

• Jutros sam bio pospan, pa sam zaboravio kišobran.

So this sentence specifically sounds like it was said by a woman.

Jutros means this morning or earlier this morning.

It refers to the morning of today, not mornings in general.

Compare:

• jutros = this morning
• ujutro = in the morning
• svako jutro = every morning

So Jutros sam bila pospana means something like I was sleepy this morning.

Here pa means something like:

• so
• and so
• then
• which is why

It connects the two ideas:

• I was sleepy this morning,
• so I forgot my umbrella.

It is very common in everyday Croatian and often sounds more natural than a very direct equivalent of English therefore.

Croatian normally does not use articles like a or the.

So kišobran can mean:

• an umbrella
• the umbrella
• sometimes even my umbrella, depending on context

In this sentence, context makes it clear that the person forgot their umbrella, even though Croatian does not have to say my.

If you wanted to make it explicit, you could say:

• zaboravila sam svoj kišobran = I forgot my umbrella

But very often that is unnecessary.

It is in the accusative singular, because it is the direct object of zaboravila.

The verb zaboraviti takes a direct object:

• zaboraviti što? = to forget what?

For masculine inanimate nouns like kišobran, the accusative singular looks the same as the nominative singular:

• nominative: kišobran
• accusative: kišobran

So even though the form does not change, its function in the sentence is accusative.

Zaboravila comes from zaboraviti, which is a perfective verb. It describes a completed event: the forgetting happened.

That fits this sentence well:

• she was sleepy,
• and as a result, she forgot the umbrella.

Zaboravljala would come from the imperfective verb zaboravljati, which usually suggests repeated, habitual, or ongoing forgetting. That would not fit as naturally here.

So:

• zaboravila = forgot (one completed act)
• zaboravljala = was forgetting / used to forget / kept forgetting, depending on context

Yes, Croatian word order is fairly flexible, but this version is very natural.

A few things are happening:

1. Jutros is placed first to set the time.
2. sam is a clitic, so it tends to appear near the beginning of its clause.
3. The sentence flows from cause to result:
   • I was sleepy
   • so I forgot the umbrella

You may also see:

• Bila sam jutros pospana, pa sam zaboravila kišobran.
• Jutros sam bila pospana pa sam zaboravila kišobran.

These are all understandable, but the original sounds very natural.

Because pospana means sleepy / drowsy, not asleep.

So:

• bila pospana = was sleepy
• spavala = was sleeping / slept

These are different ideas.

If you say:

• Jutros sam spavala = I slept this morning / I was sleeping this morning

That does not mean the same thing as:

• Jutros sam bila pospana = I was sleepy this morning

The original sentence is about her state being sleepy, which then led to forgetting the umbrella.

Yes, but the forms would change to masculine:

• Jutros sam bio pospan, pa sam zaboravio kišobran.

Changes:

• bila → bio
• pospana → pospan
• zaboravila → zaboravio

This is a very common feature of Croatian: past tense and adjectives often reflect the speaker’s gender.

Yes, in standard writing it is normally correct to put a comma before pa when it connects two clauses like this:

• Jutros sam bila pospana, pa sam zaboravila kišobran.

That is because each side has its own verb phrase:

• sam bila
• sam zaboravila

In casual writing, people may sometimes leave it out, but the comma is the standard written form here.