Την Κυριακή η κόρη της φίλης μου θέλει να πετάξει χαρταετό, ενώ ο γιος της θέλει να πάρει το πατίνι του στο πάρκο.

Την Κυριακή means on Sunday or this Sunday, with the day used as a time expression.

A few useful patterns:

• Την Κυριακή = on Sunday
• Την Δευτέρα = on Monday
• Τις Κυριακές = on Sundays / every Sunday

Greek often uses the article with days of the week in expressions of time. Here την is accusative feminine singular, because time expressions like this often use the accusative.

It means my friend’s daughter.

Breakdown:

• η κόρη = the daughter
• της φίλης = of the friend
• μου = my

So literally it is:

• the daughter of my friend

Greek often expresses possession with the genitive, where English often uses ’s.

They are not doing the same job.

1. In της φίλης μου, της is the genitive article:

   • η φίλη = the friend
   • της φίλης = of the friend

2. In ο γιος της, της is a possessive pronoun meaning her:

   • ο γιος της = her son

So one της is the, and the other της is her.

In Greek, weak possessive pronouns like μου, σου, του, της, μας, σας, τους usually come after the noun.

So:

• η φίλη μου = my friend
• το σπίτι μου = my house
• ο αδερφός της = her brother

That is the normal Greek word order. English puts my before the noun, but Greek usually puts μου after it.

θέλει να means wants to.

Structure:

• θέλει = he/she wants
• να = particle used before the verb in this kind of construction
• πετάξει / πάρει = the verb that follows

So:

• θέλει να πετάξει χαρταετό = she wants to fly a kite
• θέλει να πάρει το πατίνι του στο πάρκο = he wants to take his scooter to the park

Greek does not use an infinitive the way English does. Instead of to fly, Greek uses να + verb form.

Because after θέλει να, Greek often uses the aorist subjunctive when talking about a single complete action.

Here the idea is:

• she wants to fly a kite as one event
• he wants to take his scooter to the park as one event

So:

• να πετάξει
• να πάρει

If Greek used the present subjunctive instead, it could suggest a more ongoing, repeated, or habitual action, depending on context.

Very roughly:

• θέλει να πετάξει = she wants to fly a kite once / as an event
• θέλει να πετάει = she wants to be flying kites / to fly kites regularly / continuously

Because Greek can use a bare object noun in some expressions, especially when the meaning is general or idiomatic.

πετάω χαρταετό is a very natural way to say fly a kite.

You could also say:

• να πετάξει έναν χαρταετό = to fly a kite / one kite

But without the article, it sounds more like the general activity.

Also note the case change:

• ο χαρταετός = nominative
• τον χαρταετό = accusative
• bare object here: χαρταετό

Because the two noun phrases work differently.

• χαρταετό is part of a very natural activity expression: πετάω χαρταετό
• το πατίνι του means his scooter, and in Greek possessed nouns normally keep the definite article

So Greek usually says:

• το βιβλίο μου = my book
• το σπίτι της = her house
• το πατίνι του = his scooter

Using the article with possessed nouns is standard in Greek.

ενώ here means while.

It links the two parts of the sentence:

• the daughter wants to fly a kite,
• while the son wants to take his scooter to the park.

It can show:

• simultaneous ideas, or
• a contrast between two situations

In this sentence, it mainly connects two parallel wishes and gives a mild contrast.

Literally, it means to take his scooter to the park.

That suggests bringing it along. Depending on context, the reason is probably that he wants to use it there, but the Greek wording itself is take, not directly ride.

If Greek wanted to emphasize riding the scooter, it might use a different expression, such as:

• να πάει στο πάρκο με το πατίνι του = to go to the park on his scooter
• να κάνει πατίνι στο πάρκο = to ride/use his scooter in the park

So the sentence as written focuses on taking it with him.

Because στο is the contraction of:

• σε + το = στο

So:

• σε το πάρκο becomes στο πάρκο

This is very common in Greek:

• στο σπίτι = to/in the house
• στο σχολείο = to/at school
• στο πάρκο = to/in the park

Whether it means to or in depends on the verb and the context.

It refers to της φίλης μου — my friend.

So the sentence means:

• the daughter of my friend
• while her son

In other words, both children belong to the same friend.

Greek often avoids repeating the full noun phrase when the meaning is already clear.

Yes, Greek word order is more flexible than English word order.

This sentence begins with the time phrase:

• Την Κυριακή = On Sunday

Then it gives the first subject:

• η κόρη της φίλης μου

This is very natural. But Greek could rearrange parts of the sentence for emphasis, for example:

• Η κόρη της φίλης μου θέλει να πετάξει χαρταετό την Κυριακή...
• Ο γιος της θέλει να πάρει το πατίνι του στο πάρκο, ενώ η κόρη της φίλης μου θέλει να πετάξει χαρταετό.

The version you have is neutral and natural, especially because it sets the time first.

Here are the main ones:

• η κόρη — nominative, because it is the subject
• της φίλης — genitive, because it shows possession
• ο γιος — nominative, because it is the subject
• χαρταετό — accusative, because it is the object
• το πατίνι — accusative, because it is the object of πάρει
• στο πάρκο — after σε, so it is in the accusative form with the article contraction

For an English speaker, the most important thing is this:

• subjects are usually nominative
• possessors are often genitive
• direct objects are often accusative