Στην ουρά του αρτοποιείου στεκόμουν πίσω από μια κοπέλα που κρατούσε καπουτσίνο και ένα μικρό κουλουράκι.

Στην is the contraction of σε + την.

• σε = in / at / to
• την = the feminine singular accusative form of the

So στην ουρά literally means in the queue / in line. Greek very often combines σε with the definite article:

• σε + τον = στον
• σε + τη(ν) = στη(ν)
• σε + το = στο

Yes. Ουρά literally means tail, but it also commonly means queue / line.

The idea is similar to English expressions like the tail end of something: a line of people stretches out like a tail. So:

• στην ουρά = in the queue / in line

This is a very normal everyday use of ουρά.

Greek uses the definite article much more often than English. So where English says in line, Greek naturally says στην ουρά, literally in the queue.

That does not make it unusually specific. It is just the normal Greek way to say it.

Του αρτοποιείου is the genitive singular of το αρτοποιείο (the bakery).

Greek uses the genitive here to show a relationship like of the bakery:

• η ουρά του αρτοποιείου = the bakery’s queue / the queue at the bakery

So του αρτοποιείου tells us which queue it was.

Στεκόμουν is the 1st person singular imperfect of στέκομαι.

It means:

• I was standing
• I was standing there
• sometimes more loosely I stood, if the context is descriptive

The important thing is that it describes an ongoing situation in the past. Also, στέκομαι is one of those Greek verbs that has middle/passive-looking endings but an active meaning.

The imperfect is used for ongoing, background, or repeated actions in the past.

Here the sentence is setting the scene:

• I was standing in the bakery queue
• behind a girl
• who was holding a cappuccino and a small pastry

So στεκόμουν is not a single completed action like I stood once. It is background description: the speaker was already there, in that position.

Πίσω από means behind.

The preposition από is followed by the accusative, so we get:

• πίσω από μια κοπέλα = behind a girl

This is a fixed and very common expression in Greek.

Because the nouns have different genders.

• κοπέλα is feminine, so the indefinite article is μια
• κουλουράκι is neuter, so the indefinite article is ένα

The adjective also has to agree with the noun, so:

• ένα μικρό κουλουράκι

Here μικρό matches κουλουράκι in gender, number, and case.

Here που introduces a relative clause, so it means who, that, or which, depending on the English translation.

In this sentence:

• μια κοπέλα που κρατούσε...
• a girl who was holding...

In everyday Modern Greek, που is a very common relative word and does not change form the way English who/whom/whose can. It simply introduces the clause that describes κοπέλα.

Κρατούσε is the 3rd person singular imperfect of κρατάω / κρατώ.

It means she was holding. It is imperfect for the same reason as στεκόμουν: it describes an ongoing background action in the scene.

So the sentence paints a picture:

• I was standing
• behind a girl
• who was holding a cappuccino and a small pastry

Both actions are in progress in that past moment.

Greek can sometimes omit the article with food and drink words, especially when the focus is on the type of thing rather than on counting it as an individual object.

So:

• κρατούσε καπουτσίνο = she was holding cappuccino / a cappuccino
• κρατούσε ένα καπουτσίνο = she was holding a cappuccino

Both are possible. Adding ένα makes the single item more explicit. Leaving it out can sound a bit more compact or natural in descriptive narration.

Κουλουράκι is a diminutive form. The ending -άκι often suggests smallness, and sometimes also affection or something casual/cute.

So κουλουράκι is literally something like little ring-shaped biscuit/pastry/snack, depending on context. In food words, though, the diminutive is often just the standard everyday name and does not always feel especially emotional.

Here ένα μικρό κουλουράκι is a bit like saying a small little pastry/biscuit, with μικρό making the smallness explicit.

Yes, Greek word order is fairly flexible, and this sentence is one natural way to present the information.

Starting with Στην ουρά του αρτοποιείου sets the scene first: At/In the bakery queue... Then we get the main action: στεκόμουν. After that, the sentence adds more detail.

A different order could also be possible, for example:

• Στεκόμουν στην ουρά του αρτοποιείου πίσω από μια κοπέλα...

That would still mean essentially the same thing. The original order just sounds nicely descriptive and narrative.