Σηκώνει το φρύδι της όταν δεν πιστεύει αυτό που ακούει.

σηκώνει is the 3rd person singular present form of σηκώνω (to raise, lift).

So it means he/she/it raises. Here, the subject is understood as she from context.

Greek often uses the present tense for habitual actions. So σηκώνει here suggests something like she raises / she tends to raise rather than a one-time event only.

Greek often drops subject pronouns when they are not needed. The verb ending already tells you the person and number.

• σηκώνει = he/she/it raises
• πιστεύει = he/she/it believes
• ακούει = he/she/it hears

So Greek does not need to say αυτή (she) unless it wants to add emphasis or contrast.

Greek normally uses the definite article with nouns much more often than English does, including with body parts and possessed nouns.

So:

• το φρύδι της = her eyebrow

This is the normal Greek structure:

• article + noun + weak possessive/genitive pronoun

Without the article, it would usually sound unnatural here.

της here means her.

More specifically, it is the weak genitive pronoun of αυτή (she), and it is used to show possession:

• το φρύδι της = her eyebrow
• literally: the eyebrow of her

This is a very common Greek pattern:

• το σπίτι μου = my house
• η τσάντα σου = your bag
• το βιβλίο της = her book

Yes, Greek can use either singular or plural, depending on the exact image or nuance.

• σηκώνει το φρύδι της = she raises her eyebrow
• σηκώνει τα φρύδια της = she raises her eyebrows

The singular is very natural if the idea is that she gives that typical skeptical or surprised look by lifting one eyebrow.

So this is similar to English, where raise an eyebrow is also a common expression.

όταν means when.

It introduces a time clause:

• όταν δεν πιστεύει αυτό που ακούει = when she doesn’t believe what she hears

Because the whole sentence is in the present tense, it has a general/habitual sense:

• Whenever she doesn’t believe what she hears, she raises her eyebrow

So όταν here is not only about one single moment; it can describe a repeated reaction.

In Greek, δεν is the normal negation used with indicative verbs in the present and past-style forms.

So:

• πιστεύει = she believes
• δεν πιστεύει = she does not believe

The negative word normally comes right before the verb.

αυτό που ακούει literally means something like:

• that which she hears
• the thing that she hears

In natural English, that becomes what she hears.

Breakdown:

• αυτό = that / this thing
• που = that / which (introducing a relative clause)
• ακούει = she hears

So Greek often builds what... using a structure like:

• αυτό που...

For example:

• λέω αυτό που σκέφτομαι = I say what I think
• βλέπω αυτό που βλέπεις = I see what you see

Because αυτό here does not refer to a specific masculine or feminine noun. It means that thing in a general sense.

Greek commonly uses the neuter singular for an unspecified idea, thing, or content:

• αυτό που ακούει = the thing that she hears
• αυτό που είπε = what he/she said
• αυτό που θέλω = what I want

So the neuter is the default choice for an abstract thing or content.

It can cover both ideas, depending on context.

Greek present tense often corresponds to both:

• English simple present: hears
• English present progressive: is hearing

So αυτό που ακούει can mean:

• what she hears
• what she is hearing

In this sentence, English usually prefers what she hears, but the Greek form itself can express either, depending on the situation.

Usually it sounds like a habitual/general truth.

Because the sentence uses the present tense in both clauses:

• σηκώνει
• πιστεύει
• ακούει

it naturally suggests:

• She raises her eyebrow when she doesn’t believe what she hears
• or more explicitly:
• Whenever she doesn’t believe what she hears, she raises her eyebrow

If you wanted a one-time event in the past, Greek would normally use different forms.

Yes. Greek word order is more flexible than English word order.

For example, you could also say:

• Όταν δεν πιστεύει αυτό που ακούει, σηκώνει το φρύδι της.

That means the same thing. The difference is mainly one of focus or rhythm:

• starting with Σηκώνει το φρύδι της... puts the reaction first
• starting with Όταν δεν πιστεύει... sets up the situation first

Both are natural.

Here it clearly means believe in the sense of accept as true.

So:

• δεν πιστεύει αυτό που ακούει = she doesn’t believe what she hears

Greek πιστεύω can sometimes also relate to trust or have faith, but in this sentence it is specifically about not believing some information or statement.

The main stresses are:

• σηΚΩνει
• το ΦΡΥδι της
• όΤΑΝ
• δεν πισΤΕυει
• αυΤΟ
• που αΚΟΥει

A rough pronunciation guide:

• Σηκώνει ≈ see-KO-nee
• φρύδι ≈ FRI-thee (with δ pronounced like th in this)
• πιστεύει ≈ pee-STEV-ee
• ακούει ≈ a-KOO-ee

The written accent mark shows you where the stress falls.