Το παιδί βάζει το παιχνίδι στο σεντούκι πριν κοιμηθεί.

Because το is the definite article the, and Greek normally uses the article with each noun:

• το παιδί = the child
• το παιχνίδι = the toy
• το σεντούκι = the chest / trunk

English also uses the, but Greek is often more consistent about repeating the article with each noun phrase.

They are all neuter singular nouns. A lot of common neuter nouns in Greek end in -ι.

So here:

• παιδί = child
• παιχνίδι = toy
• σεντούκι = chest / trunk

Their article is also neuter singular: το.

Βάζει is the 3rd person singular present form of βάζω = to put.

So:

• βάζω = I put
• βάζεις = you put
• βάζει = he/she/it puts

Because the subject is το παιδί (the child), Greek uses βάζει.

Depending on context, Greek present tense can mean:

• puts
• is putting
• sometimes a habitual puts

So this sentence could describe either a general action or something happening now.

Because στο is the contracted form of σε + το.

• σε = in, on, at, to
• το = the
• σε το becomes στο

This contraction is completely normal and expected in modern Greek.

So:

• στο σεντούκι = in the chest / into the chest

In this sentence, it is best understood as into the chest, because the verb βάζει shows movement: the toy is being placed there.

Greek σε can cover several English prepositions depending on context:

• in
• into
• to
• at
• on

So the verb helps you choose the most natural English meaning.

Here is the basic case structure:

• το παιδί = nominative subject
• το παιχνίδι = accusative direct object
• στο σεντούκι = accusative after σε

A detail that often confuses learners: in the neuter singular, the nominative and accusative usually look the same. So το παιδί and το παιχνίδι do not change form visibly, even though they have different jobs in the sentence.

After πριν (before), Greek commonly uses the subjunctive, and here the verb is κοιμηθεί.

So:

• πριν κοιμηθεί = before he/she goes to sleep

Using κοιμάται would be a different structure and would not sound right here in standard Greek.

This is a very common pattern:

• πριν φύγει = before he/she leaves
• πριν φάει = before he/she eats
• πριν κοιμηθεί = before he/she goes to sleep

Κοιμηθεί is the 3rd person singular aorist subjunctive form of κοιμάμαι.

That sounds technical, but the important idea is this:

• the subjunctive is needed after πριν
• the aorist here presents the action as a single whole event

So πριν κοιμηθεί means before the child goes to sleep / falls asleep, not before the child is sleeping.

This is why the Greek feels more event-based than a literal English before sleeps.

It is understood to be the same subject as in the main clause: το παιδί.

So the sentence means:

• The child puts the toy in/into the chest before the child goes to sleep.

Greek often leaves the subject unspoken when it is already clear from context and from the verb ending.

Because Greek is a pro-drop language. That means subject pronouns are often omitted when the verb ending already shows the person.

Here, κοιμηθεί already tells you it is 3rd person singular, so Greek does not need to add he/she.

The same thing happens with βάζει. Greek does not need a separate pronoun for the child once the subject is clear.

Not as strictly as in English. Greek word order is fairly flexible, though some orders sound more natural than others.

This sentence is perfectly natural:

• Το παιδί βάζει το παιχνίδι στο σεντούκι πριν κοιμηθεί.

But Greek could also move parts around for emphasis, for example:

• Πριν κοιμηθεί, το παιδί βάζει το παιχνίδι στο σεντούκι.

That still means the same thing: Before going to sleep, the child puts the toy in the chest.

Yes. Greek often uses the definite article more regularly than English does.

In this sentence, English naturally says:

• The child puts the toy in the chest before going to sleep.

But in other contexts Greek might keep the article where English would drop it. So it is good to get used to articles being very common and important in Greek.

Here the repeated articles also help show gender, number, and case:

• το παιδί
• το παιχνίδι
• στο σεντούκι