Η αδερφή μου ξεπαγώνει τα κατεψυγμένα λαχανικά το πρωί.

In Greek, the unstressed possessive forms μου, σου, του, της, μας, σας, τους usually come after the noun.

So:

• η αδερφή μου = my sister
• literally, something like the sister my

This is normal Greek word order. You usually do not say μου αδερφή in a neutral sentence.

Greek normally uses the definite article with nouns, even when a possessive like μου is present.

So:

• η αδερφή μου = my sister
• το σπίτι μου = my house
• οι φίλοι μου = my friends

Even though English drops the, Greek keeps it.

Yes. Αδερφή is a very common Modern Greek word for sister.

You may also see αδελφή, which is a more traditional or formal variant. In everyday speech and everyday writing, αδερφή is extremely common.

So for a learner, αδερφή is absolutely normal and useful.

Ξεπαγώνει is the 3rd person singular present form of the verb ξεπαγώνω.

Here it means:

• he/she/it defrosts
• he/she/it is defrosting
• he/she/it thaws

In this sentence:

• Η αδερφή μου ξεπαγώνει... = My sister defrosts / is defrosting...

The ending -ει here shows she/he/it.

It can mean either, depending on context.

The Greek present tense often covers both:

• a habitual action: My sister defrosts the frozen vegetables in the morning
• an ongoing action: My sister is defrosting the frozen vegetables in the morning

Because of το πρωί, the sentence most naturally sounds habitual: something she does in the morning.

Because it agrees with λαχανικά.

Λαχανικά is:

• neuter
• plural
• here, accusative (the direct object)

So the adjective must match it:

• κατεψυγμένα λαχανικά = frozen vegetables

The dictionary form would be something like:

• κατεψυγμένος = masculine singular
• κατεψυγμένη = feminine singular
• κατεψυγμένο = neuter singular

The neuter plural form is κατεψυγμένα.

Greek often uses the definite article where English may or may not use the.

So τα κατεψυγμένα λαχανικά is a normal noun phrase meaning:

• the frozen vegetables

In some contexts, Greek can leave the article out, but with a concrete object like this, the article sounds very natural and standard.

In Greek, adjectives often come before the noun:

• τα κατεψυγμένα λαχανικά = the frozen vegetables

That is a very common and neutral order.

Greek can sometimes place adjectives after the noun too, but article + adjective + noun is one of the most basic patterns learners should get used to.

Το πρωί literally means the morning, but as a time expression it means:

• in the morning
• sometimes, depending on context, this morning

Greek often uses the accusative of time without a preposition for expressions like this.

So:

• το πρωί = in the morning
• το βράδυ = in the evening / at night
• την Κυριακή = on Sunday

This is just a normal Greek time-expression pattern.

No, Greek word order is fairly flexible.

The sentence as written:

• Η αδερφή μου ξεπαγώνει τα κατεψυγμένα λαχανικά το πρωί.

is a neutral, natural order: subject + verb + object + time expression

But Greek could also move parts around for emphasis, for example:

• Το πρωί η αδερφή μου ξεπαγώνει τα κατεψυγμένα λαχανικά.
• Τα κατεψυγμένα λαχανικά τα ξεπαγώνει η αδερφή μου το πρωί.

The basic meaning stays similar, but the emphasis changes.

A rough pronunciation guide is:

ee a-ther-FEE moo kse-pa-GHO-nee ta ka-tep-sig-ME-na la-ha-nee-KA to pro-EE

A few useful sound notes:

• η sounds like ee
• ξ sounds like ks
• γ in ξεπαγώνει is a soft Greek sound, not a hard English g
• χ in λαχανικά is like the ch in German Bach or Scottish loch
• the stress falls where the accent marks are:
  αδερφή, ξεπαγώνει, κατεψυγμένα, λαχανικά

A few clues help:

1. Η αδερφή μου is in the nominative form, which is the normal subject form.
2. ξεπαγώνει is 3rd person singular, which matches η αδερφή = she.
3. τα κατεψυγμένα λαχανικά is the thing being defrosted, so it functions as the direct object.

So the structure is:

• Η αδερφή μου = subject
• ξεπαγώνει = verb
• τα κατεψυγμένα λαχανικά = direct object
• το πρωί = time expression