Στο πάρκο φορούσα γιλέκο το πρωί, αλλά το μεσημέρι έμεινα μόνο με βερμούδα και κοντομάνικη μπλούζα.

Στο is the very common contraction of σε + το.

• σε = in, at, to
• το = the

So στο πάρκο means in the park or at the park.

Greek regularly combines σε with the definite article:

• σε + το = στο
• σε + τη(ν) = στη(ν)
• σε + τα = στα

Greek usually drops subject pronouns when they are not needed, because the verb ending already shows the person.

• φορούσα = I was wearing
• έμεινα = I remained / I ended up / I was left

So Greek does not need εγώ here. You could add εγώ for emphasis, but in a neutral sentence it is normally omitted.

Φορούσα is the imperfect tense. Here it describes an ongoing state in the past: what the speaker was wearing during the morning.

So:

• φορούσα = I was wearing
• φόρεσα = I put on / I wore in a single completed event

In this sentence, the idea is not that the speaker put on a vest in the morning, but that they had it on during that time. That is why φορούσα is the natural choice.

Literally, έμεινα is the aorist of μένω, which often means I stayed or I remained. But in this sentence it has the sense of:

• I ended up
• I was left
• I remained

So έμεινα μόνο με βερμούδα και κοντομάνικη μπλούζα means something like:

• I ended up wearing only shorts and a short-sleeved top
• I was left with only shorts and a short-sleeved top on

It shows a change from the earlier situation: in the morning there was also a vest, but by noon that was no longer the case.

They are in the accusative, but for several of these nouns the accusative looks exactly like the nominative.

Here is how they work:

• στο πάρκο: πάρκο is accusative after σε / στο
• φορούσα γιλέκο: γιλέκο is accusative as the direct object of φορούσα
• με βερμούδα και κοντομάνικη μπλούζα: βερμούδα and μπλούζα are accusative after με

This can be confusing because:

• many neuter nouns have the same form in nominative and accusative
• many feminine nouns in -α also look the same in nominative and accusative singular

So the function is often shown by the verb or preposition, not by a visibly different noun ending.

Greek often leaves out the indefinite article in this kind of sentence, especially when talking about clothing in a general, natural way.

So:

• φορούσα γιλέκο = I was wearing a vest
• με βερμούδα = with shorts on / wearing shorts
• κοντομάνικη μπλούζα = a short-sleeved top

Greek often sounds more natural with the bare noun here than with ένα / μια.

You can say:

• φορούσα ένα γιλέκο
• με μια βερμούδα και μια κοντομάνικη μπλούζα

but that is a little more explicit and can sound slightly more marked, depending on context.

In Greek, many time expressions use the definite article in an adverbial way.

So:

• το πρωί = in the morning
• το μεσημέρι = at noon / around midday
• similarly, το βράδυ = in the evening / at night

This is very normal Greek usage. English usually uses a preposition, but Greek often uses article + time noun instead.

Yes. In Greek, η βερμούδα is commonly singular even though in English we usually say shorts.

So:

• μια βερμούδα = one pair of Bermuda shorts
• βερμούδες = multiple pairs of Bermuda shorts

This is one of those places where Greek and English organize clothing words differently.

It is one item.

• κοντομάνικη = short-sleeved
• μπλούζα = blouse / top / shirt

So κοντομάνικη μπλούζα means a short-sleeved top/shirt.

The adjective κοντομάνικη agrees with μπλούζα in gender, number, and case:

• μπλούζα is feminine singular
• so the adjective is also feminine singular: κοντομάνικη

Literally, μόνο με means only with, but in this context it means something like:

• wearing only
• with nothing but
• left in only

So the phrase:

έμεινα μόνο με βερμούδα και κοντομάνικη μπλούζα

means that by noon the speaker had reduced what they were wearing to just those two items.

Greek word order is more flexible than English word order. Putting Στο πάρκο first sets the scene immediately:

• At the park / In the park, ...

That gives the location as the background before the sentence tells you what happened.

You could move it later, for example:

• Φορούσα γιλέκο το πρωί στο πάρκο...

but the original version sounds natural because it opens with the setting.

Either can work, depending on context.

Greek σε / στο covers a range of meanings that English splits into several prepositions. So στο πάρκο can mean:

• in the park if you are thinking of being physically inside the park
• at the park if you are thinking more generally about location

Both are good English translations.

Yes. The imperfect can describe either:

• an ongoing past situation: I was wearing
• a habitual past action: I used to wear

In this sentence, because of the contrast between το πρωί and το μεσημέρι, the most natural reading is the ongoing one:

• In the morning, I was wearing a vest, but by noon...

But grammatically, φορούσα is the tense that can also express habitual meaning in other contexts.