Στην τηλεδιάσκεψη μιλάω πιο αργά, για να καταλαβαίνουν όλοι.

Στην is the contraction of σε + την:

• σε = in / at / to
• την = the (feminine accusative singular)

So:

• στην τηλεδιάσκεψη = in the videoconference / during the video call

In this sentence, it sets the context: during the videoconference.

Τηλεδιάσκεψη is a feminine noun, and after σε Greek normally uses the accusative case.

So:

• η τηλεδιάσκεψη = the videoconference (nominative)
• την τηλεδιάσκεψη = the videoconference (accusative)
• στην τηλεδιάσκεψη = in the videoconference

This is very common after σε.

Greek often drops subject pronouns when they are not needed, because the verb ending already shows the person.

• μιλάω = I speak / I am speaking

So Greek does not need εγώ unless you want emphasis:

• Εγώ μιλάω πιο αργά = I speak more slowly (as for me / I do)

Without εγώ, the sentence sounds natural and neutral.

Μιλάω means I speak / I am speaking.

Here it fits naturally because the sentence is about the way the speaker talks during a videoconference.

• μιλάω πιο αργά = I speak more slowly

A learner might wonder about λέω, but λέω means I say. Greek distinguishes these just like English often does:

• μιλάω = speak, talk
• λέω = say

So in this sentence, μιλάω is the right choice.

Πιο means more, and αργά is the adverb slowly.

So:

• αργά = slowly
• πιο αργά = more slowly

This is the normal way to form a comparative adverb in Greek.

Compare:

• μιλάω αργά = I speak slowly
• μιλάω πιο αργά = I speak more slowly

Here it is an adverb, because it describes how the speaker talks.

• αργός / αργή / αργό = slow (adjective)
• αργά = slowly (adverb)

In the sentence:

• μιλάω πιο αργά = I speak more slowly

So αργά modifies the verb μιλάω.

Usually, no.

• πιο αργά = more slowly
• αργότερα = later

So these are different ideas:

• Μιλάω πιο αργά = I speak more slowly
• Μιλάω αργότερα = I speak later

This is a very common learner confusion.

Για να means so that / in order to. It introduces a purpose clause.

So:

• μιλάω πιο αργά, για να καταλαβαίνουν όλοι
• I speak more slowly, so that everyone can understand

This construction is extremely common in Greek:

• διαβάζω για να μάθω = I study in order to learn
• έρχομαι νωρίς για να βοηθήσω = I come early to help

After να, Greek uses the verb form associated with the subjunctive environment. In Modern Greek, this often looks like the ordinary present form, but what matters is the structure with να.

• καταλαβαίνουν = they understand / they are understanding

Here it means:

• so that they understand
• or more naturally in English, so that everyone can understand

Because the sentence is talking about an ongoing situation during the videoconference, the imperfective idea makes sense: the speaker talks slowly so people can keep following what is being said.

This is a very good question.

Greek όλοι is grammatically plural, literally all (people). So the verb is plural too:

• όλοι καταλαβαίνουν = everyone understands / all understand

English uses singular everyone, but Greek is thinking more like all people.

So:

• όλοι → plural
• καταλαβαίνουν → plural verb

That is completely normal Greek.

Greek word order is more flexible than English. Both of these are possible:

• για να καταλαβαίνουν όλοι
• για να όλοι καταλαβαίνουν ← much less natural here

The version with όλοι after the verb sounds natural and smooth in this sentence.

Greek often places the subject after the verb, especially when the subject is not the main focus.

So καταλαβαίνουν όλοι is a natural way to say everyone understands / everyone can understand.

Yes, and the difference is about aspect.

• για να καταλαβαίνουν όλοι suggests ongoing understanding:
  so that everyone can follow / understand as we go
• για να καταλάβουν όλοι suggests reaching understanding as a result:
  so that everyone understands / gets it

In many contexts, both are possible, but they are not exactly identical.

In this videoconference sentence, καταλαβαίνουν feels very natural because the idea is continuous comprehension while the speaker is talking.

The comma separates the main clause from the purpose clause.

• Στην τηλεδιάσκεψη μιλάω πιο αργά = main clause
• για να καταλαβαίνουν όλοι = purpose clause

Greek punctuation often uses a comma here, just as English often does before so that or in order that.

Literally, yes, but in natural English it often means:

• during the videoconference
• on the video call
• in the video meeting

Greek σε + event/time-context noun often expresses the setting where something happens, not only physical location.

So the Greek is very natural even if the best English translation is not word-for-word.

Yes. Both are correct in Modern Greek.

• μιλάω
• μιλώ

Both mean I speak.
μιλάω is often felt as more common in everyday speech, while μιλώ can sound slightly more formal or concise, but both are standard.

So you may also see:

• Στην τηλεδιάσκεψη μιλώ πιο αργά...

A natural rhythm would usually emphasize the useful information:

• Στην τηλεδιάσκεψη μιλάω πιο αργά, για να καταλαβαίνουν όλοι.

Possible focus points:

• τηλεδιάσκεψη if contrasting with other situations
• πιο αργά if the important point is the slower speed
• όλοι if emphasizing inclusiveness

For example:

• Στην τηλεδιάσκεψη μιλάω πιο αργά = the important point is that I slow down in that setting
• ...για να καταλαβαίνουν όλοι = the reason is that everyone should be able to follow

Probably these three:

1. σε + article often contracts

   • σε την → στην

2. πιο + adverb/adjective makes a comparative

   • πιο αργά = more slowly

3. για να + verb expresses purpose

   • για να καταλαβαίνουν όλοι = so that everyone can understand

If you remember those three patterns, you can build many similar Greek sentences.