Η γιαγιά μου μου έδειξε πώς να περνάω το νήμα στη βελόνα πριν αρχίσω να ράβω.

Because they do two different jobs:

• η γιαγιά μου = my grandmother
  Here, μου is a possessive pronoun: my.
• μου έδειξε = showed me
  Here, μου is an indirect object pronoun: to me / me.

So the sentence literally contains:

• the grandmother my
• to-me showed

This is completely normal in Greek.

Greek usually uses the definite article with nouns much more often than English does, including family words:

• η γιαγιά μου = my grandmother
• ο πατέρας μου = my father
• η αδερφή μου = my sister

If you say Γιαγιά μου! without the article, that often sounds like direct address:

• Γιαγιά μου! = Grandma!

So in this sentence, Η γιαγιά μου is the normal way to say my grandmother as the subject.

Έδειξε is the aorist form of δείχνω (to show), so it means showed.

A few things are happening here:

• δείχνω = I show / I am showing
• έδειξε = he/she showed

The έ- at the beginning is the past-tense augment, which often appears in past forms in Greek.

So:

• μου έδειξε = showed me

Greek uses the aorist here because this is a single completed past action: the grandmother showed the speaker how to do something.

In this sentence, πώς να means how to.

So:

• πώς να περνάω το νήμα στη βελόνα
  = how to thread the needle or more literally: = how to pass the thread into the needle

This is a very common Greek pattern:

• μου είπε πώς να το κάνω = he/she told me how to do it
• μαθαίνω πώς να μαγειρεύω = I’m learning how to cook

So πώς να + verb is one of the standard ways to say how to ... in Greek.

This is about aspect, which is very important in Greek.

• περνάω = imperfective
• περάσω = perfective

Here, πώς να περνάω το νήμα στη βελόνα focuses on the process / method of doing it, not just one single completed threading. That is why the imperfective περνάω makes sense.

Compare:

• πώς να περνάω το νήμα στη βελόνα
  = how to thread the needle, how to do this process
• πώς να περάσω το νήμα στη βελόνα
  = how to get the thread through the needle, possibly referring more to one completed act

In real life, both kinds of choices can appear depending on what nuance the speaker wants, but in this sentence περνάω emphasizes the skill or procedure.

Yes. Περνάω and περνώ are two common forms of the same verb.

Both mean I pass / I thread / I go through, depending on context.

So you may also see:

• πώς να περνώ το νήμα στη βελόνα

That is not a different verb, just a different form/style of the same one.

Greek expresses this idea as pass the thread into the needle.

So:

• το νήμα = the thread
  This is the direct object.
• στη βελόνα = into the needle / in the needle
  This is σε + τη(ν) βελόνα.

So literally:

• περνάω το νήμα στη βελόνα
  = I pass the thread into the needle

English usually says thread the needle, but Greek often phrases it with thread + into needle.

Στη is the contracted form of:

• σε + τη(ν)

So:

• στη βελόνα = in/into the needle

In modern Greek writing and speech, the final -ν in την is sometimes kept and sometimes dropped depending on the following sound and style.

That means you may see both:

• στη βελόνα
• στην βελόνα

In everyday language, στη βελόνα is very natural.

Because πριν (before) is followed here by a subjunctive-style form referring to a specific event:

• αρχίσω = I start / I should start in this kind of structure

Greek uses the aorist subjunctive here because the idea is:

• before I start sewing

That is a single, bounded action: the moment of starting.

So:

• πριν αρχίσω = before I start

Using αρχίζω would not fit this structure.

Good question. Greek can use both:

• πριν αρχίσω
• πριν να αρχίσω

Both are possible in modern Greek, and the version without να is very common.

So in this sentence:

• πριν αρχίσω να ράβω = before I start sewing

There is nothing wrong with the missing να. It is just a normal Greek pattern.

Again, this is an aspect choice.

• ράβω = imperfective → ongoing activity, the process of sewing
• ράψω = perfective → one completed sewing action

After αρχίσω (start), Greek often uses the imperfective to describe the activity that begins:

• να αρχίσω να ράβω = to start sewing

This is like focusing on the activity as something ongoing.

Compare:

• άρχισα να διαβάζω = I started reading
• άρχισα να γράφω = I started writing
• άρχισα να ράβω = I started sewing

So ράβω is the natural choice here.

Because Greek verb endings usually already show the person.

• αρχίσω = I start
• ράβω = I sew / am sewing

So Greek often leaves out subject pronouns like εγώ unless they are needed for emphasis or contrast.

That means:

• πριν αρχίσω να ράβω
  naturally means
  before I start sewing

without needing εγώ.

Yes. Greek word order is more flexible than English, because the endings and articles carry a lot of grammatical information.

For example, the original order:

• Η γιαγιά μου μου έδειξε πώς να περνάω το νήμα στη βελόνα πριν αρχίσω να ράβω.

is neutral and natural.

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

• Πριν αρχίσω να ράβω, η γιαγιά μου μου έδειξε πώς να περνάω το νήμα στη βελόνα.

That puts more focus on before I start sewing.

So the exact order can change, but the original sentence is perfectly normal.

Yes — very much so. This sentence contains several aspect choices:

• έδειξε = completed past action
• περνάω = process / method
• αρχίσω = single starting point
• ράβω = ongoing activity

So Greek is not only telling you when things happen, but also how the speaker sees the action:

• as completed
• as ongoing
• as repeated
• as a single event

This is one of the biggest differences English speakers notice when learning Greek.