Η εγγονή της μοιάζει στη γιαγιά της όταν χαμογελάει.

Η is the feminine singular definite article, meaning the.

So η εγγονή = the granddaughter.

Greek articles change for gender, number, and case, so you will see different forms like ο, η, το, οι, τα, τη, την, etc.

Both instances of της mean her.

• Η εγγονή της = her granddaughter
• στη γιαγιά της = to / like her grandmother

In Greek, possessive words like my, your, his, her are often expressed with these short genitive clitic forms after the noun:

• η μητέρα μου = my mother
• ο αδερφός της = her brother

So the sentence literally contains her granddaughter and her grandmother.

Because Greek normally places these short possessive forms after the noun:

• η φίλη μου = my friend
• ο πατέρας σου = your father
• η εγγονή της = her granddaughter

This is one of the basic word-order differences between English and Greek.

Because the verb μοιάζω normally takes σε + accusative when it means resemble / look like someone.

So:

• μοιάζω σε κάποιον = I look like / resemble someone

Here:

• σε τη γιαγιά της contracts to στη γιαγιά της

So μοιάζει στη γιαγιά της literally means she resembles her grandmother.

στη is the contraction of:

• σε
  • τη

So:

• σε τη γιαγιά → στη γιαγιά

This is very common in Greek:

• σε το → στο
• σε την often appears as στη(ν) depending on style and pronunciation

In this sentence, στη γιαγιά is the normal contracted form.

It is in the accusative singular after σε.

The base noun is:

• η γιαγιά = nominative

After σε, it becomes:

• τη γιαγιά = accusative
• στη γιαγιά = σε + τη γιαγιά

So even though English just says like her grandmother, Greek uses a structure that includes σε.

They are both in the present tense, third person singular:

• μοιάζει = she looks like / resembles
• χαμογελάει = she smiles / is smiling

In a sentence with όταν, the Greek present can describe a general situation or a repeated one:

• όταν χαμογελάει = when she smiles

This is a very natural question, because the Greek sentence is ambiguous.

χαμογελάει means he/she smiles, and Greek often leaves the subject unstated because the verb ending already tells you it is third person singular.

So όταν χαμογελάει could mean:

• when the granddaughter smiles
• or, depending on context, when the grandmother smiles

Very often, readers will assume it refers to the main subject, the granddaughter, unless context suggests otherwise. But the sentence by itself can be unclear.

If you want to make it explicit, you could say:

• όταν χαμογελάει η εγγονή = when the granddaughter smiles
• όταν χαμογελάει η γιαγιά = when the grandmother smiles

Yes, both χαμογελάει and χαμογελά are correct in Modern Greek.

This happens with many verbs in -άω / -ώ. They often have two present-tense forms:

• αγαπά / αγαπάει
• μιλά / μιλάει
• χαμογελά / χαμογελάει

So in this sentence, όταν χαμογελάει and όταν χαμογελά are both acceptable.

Usually μοιάζω σε κάποιον means to resemble someone, often in appearance, but it can also suggest similarity in manner or expression depending on context.

Because this sentence adds όταν χαμογελάει, it strongly suggests resemblance in facial expression or appearance when smiling.

So it is not just a dictionary meaning in isolation; the context shapes it.

No, Greek word order is more flexible than English word order.

The neutral order here is:

• Η εγγονή της μοιάζει στη γιαγιά της όταν χαμογελάει.

But Greek could rearrange parts for emphasis, for example:

• Στη γιαγιά της μοιάζει η εγγονή της όταν χαμογελάει.

That still means essentially the same thing, but the emphasis shifts.

Even so, the original version sounds like a normal, neutral sentence.

Grammatically, της is the genitive form of the third-person feminine pronoun, and in sentences like this it functions as a possessive clitic.

So in learner-friendly terms, yes, it works like her.

But Greek does not use a separate word exactly equivalent to an English possessive adjective in this position. Instead, it uses this short genitive form after the noun:

• το βιβλίο της = her book
• η γιαγιά της = her grandmother

Yes, in theory they could, because της just means her and Greek does not automatically mark whether the two hers are the same person.

So depending on context, the sentence could mean:

• her granddaughter resembles her grandmother
• or something like one woman’s granddaughter resembles another woman’s grandmother

But without special context, most people will naturally understand both της forms as referring to the same woman.