Στο σπίτι είχαμε τσουρέκι και λουκουμάδες, οπότε όλοι έγιναν γρήγορα χορτάτοι.

Because στο is the contracted form of σε το.

• σε = in / at / to
• το = the for a neuter singular noun

So:

• σε το σπίτι → στο σπίτι

This contraction is standard in modern Greek. You will also often see:

• στη(ν) = σε την
• στον = σε τον
• στους = σε τους

Στο σπίτι literally means in the house or at the house, but in many contexts it is naturally understood as at home.

Greek often uses σπίτι with the article in this kind of everyday expression:

• στο σπίτι = at home / in the house

Which English translation sounds best depends on context. In this sentence, at home is probably the most natural.

Because the sentence is talking about the past.

• έχουμε = we have
• είχαμε = we had

So είχαμε τσουρέκι και λουκουμάδες means that, at that time, those foods were available or present.

Also, είχαμε is the imperfect form of έχω. In a sentence like this, it can describe the situation in the background: we had some food at home, and as a result something happened next.

Greek distinguishes not just time, but also aspect.

Here, είχαμε is imperfect because it presents the food as a state or situation that existed in the past:

• At home, we had tsoureki and loukoumades...

The focus is not on the moment of getting the food, but on the fact that it was there. Then the second clause gives the result:

• ...so everyone became full quickly.

So the pattern is very natural:

• background/state: είχαμε
• event/result: έγιναν

That is just how the speaker is choosing to refer to the food.

• τσουρέκι is singular: one loaf / one type / some tsoureki
• λουκουμάδες is plural: multiple pieces

Food words often work this way. A speaker may use the singular for something viewed as one whole item, and the plural for something naturally thought of as separate pieces.

So this is completely normal Greek, just as English might say:

• We had cake and donuts

with one item singular and the other plural.

Οπότε is a connector meaning so, therefore, as a result, or which is why, depending on context.

Here it introduces the consequence of the first clause:

• We had tsoureki and loukoumades, so everyone quickly became full.

It is very common in spoken and written Greek for linking cause and result.

Yes, this is a very common point for English speakers.

Greek όλοι is grammatically plural, meaning all (of them/us/you) or everyone in a group sense.

So Greek says:

• όλοι έγιναν χορτάτοι = everyone became full

Even though English often treats everyone as grammatically singular, Greek uses a plural form here because it is thinking of the people as a group of multiple individuals.

Also, όλοι is masculine plural, which is used for:

• a group of men
• a mixed group
• a group whose gender is not being specified

If the group were all female, you would say:

• όλες έγιναν χορτάτες

Because έγιναν means became, while ήταν means were.

• έγιναν χορτάτοι = they became full
• ήταν χορτάτοι = they were full

In this sentence, the idea is that after eating, a change happened: they moved into the state of being full. That is why γίνομαι (become) is used rather than είμαι (be).

Έγιναν is the aorist, 3rd person plural, of γίνομαι.

• dictionary form: γίνομαι = become
• aorist stem: έγινα
• 3rd plural: έγιναν = they became

This is an important verb because it is very common and a little irregular, so it is worth memorizing.

A few useful forms are:

• έγινα = I became
• έγινες = you became
• έγινε = he/she/it became
• έγιναν = they became

Because it describes the subject όλοι.

Χορτάτος / χορτάτη / χορτάτο means full / satisfied from eating. Here it is a predicate adjective, so it agrees with the subject in gender and number.

Since the subject is όλοι:

• masculine plural subject → χορτάτοι

Examples:

• Ο Γιάννης είναι χορτάτος.
• Η Μαρία είναι χορτάτη.
• Τα παιδιά είναι χορτάτα.
• Όλοι έγιναν χορτάτοι.

So the ending changes because Greek adjectives must agree with the noun or pronoun they describe.

Γρήγορα is an adverb meaning quickly. Here it modifies έγιναν χορτάτοι:

• they became full quickly

Its position is natural, but Greek word order is fairly flexible. You could move it for emphasis, though some versions may sound more natural than others.

For example:

• όλοι έγιναν γρήγορα χορτάτοι
• όλοι γρήγορα έγιναν χορτάτοι

The sentence you were given is a very normal placement.

Because Greek verbs usually already show the subject in their endings.

• είχαμε itself means we had

So Greek often omits subject pronouns unless they are needed for emphasis or contrast.

For example:

• Είχαμε τσουρέκι. = We had tsoureki.
• Εμείς είχαμε τσουρέκι. = We had tsoureki (with emphasis on we)

This is why Greek sentences often look shorter than their English equivalents.

Because the sentence has two clauses:

1. Στο σπίτι είχαμε τσουρέκι και λουκουμάδες
2. οπότε όλοι έγιναν γρήγορα χορτάτοι

The comma helps separate the first statement from the result clause introduced by οπότε. This is very normal punctuation in Greek, just as in English you often write:

• ..., so ...