Η γιαγιά ψιθυρίζει όταν μιλάει με το μωρό.

Greek uses definite articles very regularly, often more often than English does.

• η γιαγιά = the grandma / grandmother
• το μωρό = the baby

These article forms also show grammatical gender:

• η = feminine singular
• το = neuter singular

So the articles are not optional decoration; they are a normal part of how Greek nouns are built in a sentence.

Η γιαγιά is the subject of the sentence, so it is in the nominative case.

Breakdown:

• η = feminine singular nominative article
• γιαγιά = feminine singular noun, meaning grandma / grandmother

Because η γιαγιά is the one doing the action, it appears in the nominative.

Both are third person singular present tense verb forms, meaning she whispers and she talks/is talking.

• ψιθυρίζει comes from ψιθυρίζω = to whisper
• μιλάει comes from μιλάω / μιλώ = to speak, to talk

Since the subject is η γιαγιά = she, both verbs appear in the he/she/it form.

So:

• ψιθυρίζει = she whispers / is whispering
• μιλάει = she talks / is talking

Both μιλάει and μιλά are correct.

• μιλάει is very common in everyday Greek
• μιλά is also standard and slightly shorter

So these are both fine:

• Η γιαγιά ψιθυρίζει όταν μιλάει με το μωρό.
• Η γιαγιά ψιθυρίζει όταν μιλά με το μωρό.

The meaning does not really change.

Όταν means when. In sentences like this, it often has the sense of whenever.

So the sentence can be understood as:

• Grandma whispers when/whenever she talks with the baby.

After όταν, Greek normally uses an ordinary finite verb form, not a special infinitive or English-style -ing form. So όταν μιλάει is exactly what you would expect.

With μιλάω, Greek can use different prepositions depending on the nuance.

• μιλάω με κάποιον = talk with someone
• μιλάω σε κάποιον = speak to someone

In your sentence, με το μωρό presents it as interaction with the baby, which sounds very natural.

Also, note that σε το usually contracts to στο:

• μιλάει στο μωρό = she talks to the baby
• μιλάει με το μωρό = she talks with the baby

Both can be possible, but με is the form actually used in this sentence.

After με, Greek uses the accusative case.

So το μωρό here is accusative. For this noun, the accusative looks the same as the nominative, so there is no visible change:

• nominative: το μωρό
• accusative: το μωρό

That is very common with neuter singular nouns in Greek.

Grammatically, the Greek present can do both, just like English present forms can in some contexts.

In this sentence, the most natural reading is habitual:

• Grandma whispers whenever she talks with the baby.

So it sounds more like a repeated behavior than one single event happening at this exact moment.

Yes. Greek often drops subject pronouns and sometimes even the full subject noun phrase if the meaning is already clear from context.

So if everyone already knows who is being discussed, you could say:

• Ψιθυρίζει όταν μιλάει με το μωρό.

That would mean She whispers when she talks with the baby.

But keeping Η γιαγιά makes the sentence clearer and more self-contained.

The word order can change more freely than in English.

Your sentence is the neutral order:

• Η γιαγιά ψιθυρίζει όταν μιλάει με το μωρό.

But you could also say:

• Όταν μιλάει με το μωρό, η γιαγιά ψιθυρίζει.

That version puts more focus on the when clause first. The basic meaning stays the same.

A simple pronunciation guide is:

• Η γιαγιά → ee ya-YA
• ψιθυρίζει → psee-thee-REE-zee
• όταν → O-tan
• μιλάει → mee-LA-ee
• με το μωρό → meh to mo-RO

A few useful pronunciation notes:

• ψ is pronounced ps, as in the end of lips
• για sounds roughly like ya
• the written accent mark shows which syllable is stressed:
  • γιαγιά
  • ψιθυρίζει
  • όταν
  • μιλάει
  • μωρό

Ψιθυρίζει specifically means whispers.

So it is stronger and more specific than just speaks softly. If Greek wanted to say she speaks softly/quietly, it could use a different expression, such as:

• μιλάει σιγά
• μιλάει χαμηλόφωνα

But ψιθυρίζει clearly gives the idea of whispering.