Η εφαρμογή μου στέλνει ειδοποίηση κάθε δύο ώρες.

Here μου means my.

In Greek, possession is often shown with a weak pronoun after the noun:

• η εφαρμογή μου = my app
• literally, something like the app of mine

So Greek usually says the app my rather than putting my before the noun the way English does.

μου is very common in this structure:

• το σπίτι μου = my house
• ο φίλος μου = my friend
• η ιδέα μου = my idea

Greek normally uses the definite article much more often than English.

So for a possessed noun, Greek typically says:

• η εφαρμογή μου = my app

not just:

• εφαρμογή μου

The article agrees with the noun in gender, number, and case:

• η for feminine singular
• εφαρμογή is a feminine singular noun

So η εφαρμογή μου is the standard way to say my app.

στέλνει is the 3rd person singular form of στέλνω = to send.

It is used because the subject is η εφαρμογή μου = my app, which is it in English.

So:

• στέλνω = I send
• στέλνεις = you send
• στέλνει = he/she/it sends

Since the app is doing the action, Greek uses στέλνει = it sends.

Greek present tense is often used for habitual or repeated actions, just like in English.

So:

• Η εφαρμογή μου στέλνει ειδοποίηση κάθε δύο ώρες.

means the app regularly sends a notification every two hours.

It does not have to mean it is sending one right this second. It can describe a general pattern or setting.

Greek often leaves out the article with a direct object when it means a/an in a general sense.

So:

• στέλνει ειδοποίηση = sends a notification

This sounds natural when talking about what the app does regularly.

If you said:

• στέλνει μια ειδοποίηση

that would also be correct, but it puts a bit more emphasis on one notification each time.

So both can work, but the version without μια is perfectly normal.

Yes, ειδοποίηση is the direct object, so here it is in the accusative.

The reason it looks unchanged is that many feminine nouns in -η have the same form in the nominative singular and accusative singular.

So:

• nominative: η ειδοποίηση = the notification
• accusative: την ειδοποίηση = the notification

Without the article, the bare noun is still ειδοποίηση, so the form does not visibly change.

κάθε means every / each.

When Greek wants to say every two hours, it uses:

• κάθε + number + plural noun

So:

• κάθε δύο ώρες = every two hours
• κάθε τρεις μέρες = every three days
• κάθε πέντε λεπτά = every five minutes

This is a very common pattern.

Because the sentence says two hours, not one hour.

After numbers greater than one, Greek normally uses the noun in the plural:

• δύο ώρες = two hours
• τρεις μέρες = three days

So with κάθε δύο..., the noun stays plural:

• κάθε δύο ώρες

Compare:

• κάθε ώρα = every hour
• κάθε δύο ώρες = every two hours

Yes. δυο and δύο are both used for two.

• δύο is the more formal/full spelling
• δυο is very common in everyday writing and speech

So both of these are fine:

• κάθε δύο ώρες
• κάθε δυο ώρες

Yes, in some contexts.

• στέλνει ειδοποίηση κάθε δύο ώρες = sends a notification every two hours
• στέλνει ειδοποιήσεις = sends notifications

The singular ειδοποίηση works well when you mean one notification at each interval. The plural ειδοποιήσεις is more general and may sound less tied to a one-at-a-time schedule.

So for this sentence, ειδοποίηση is a natural choice.

The given word order is very natural:

• Η εφαρμογή μου στέλνει ειδοποίηση κάθε δύο ώρες.

But Greek word order is fairly flexible, especially when the meaning is already clear.

For example, these are also possible:

• Κάθε δύο ώρες η εφαρμογή μου στέλνει ειδοποίηση.
• Ειδοποίηση στέλνει η εφαρμογή μου κάθε δύο ώρες.

The original sentence is the most neutral and straightforward. Changing the order usually changes emphasis, not the basic meaning.

Yes, it is natural and correct.

Depending on context, Greek speakers might also say things like:

• στέλνει μια ειδοποίηση
• μου στέλνει ειδοποίηση = sends me a notification
• βγάζει ειδοποίηση = shows/pops up a notification

But the sentence you have is a perfectly normal way to express the idea that an app sends a notification at regular intervals.