Η καινούρια συνάδελφός μου μιλάει χαμηλόφωνα, αλλά πολύ καθαρά.

Because not every Greek noun ending in -ος is masculine. Συνάδελφος is a very common noun that can refer to either a man or a woman.

In this sentence, it is feminine because the article is η and the adjective is καινούρια, both feminine:

• η = feminine the
• καινούρια = feminine new
• συνάδελφος = colleague

So the gender is shown mainly by the words around the noun, not by the ending alone.

Καινούρια is the feminine singular form of the adjective καινούριος / καινούρια / καινούριο.

It has to agree with συνάδελφος, which is feminine here. That is why you get:

• η καινούρια συνάδελφος

If the colleague were male, you would say:

• ο καινούριος συνάδελφος

So this is a normal case of adjective agreement in gender and number.

Μου means my here.

Greek usually expresses this kind of possession with a weak pronoun placed after the noun:

• η συνάδελφός μου = my colleague

So Greek often says something closer to:

• the colleague of mine

This is completely normal. English puts my before the noun, but Greek commonly puts μου after it.

This is because μου is an enclitic, meaning it is a very weak word that leans on the word before it.

When a Greek word is stressed on the antepenultimate syllable, like συνάδελφος, and an enclitic follows, Greek spelling often adds a second accent:

• συνάδελφος
• συνάδελφός μου

This does not mean the word has changed form in some major grammatical way. It is mainly a stress/orthography rule triggered by the enclitic μου.

You see the same thing in phrases like:

• ο δάσκαλός μου
• ο άνθρωπός μου

Because Greek normally does not use subject pronouns unless they are needed for emphasis or contrast.

Here, the subject is already clearly stated:

• Η καινούρια συνάδελφός μου

So there is no need to add αυτή.

If you did add αυτή, it would sound emphatic, something like:

• She speaks softly, but very clearly

In other words, Greek often leaves out subject pronouns when the subject is already obvious.

Yes. Both μιλάει and μιλά are correct.

They are two common present-tense forms of the verb μιλάω / μιλώ, meaning to speak. So:

• μιλάει = speaks / is speaking
• μιλά = speaks / is speaking

In everyday Greek, both are very common. Μιλάει may sound a little fuller or more explicit in form, but there is no difference in basic meaning here.

They are adverbs in this sentence. They describe how she speaks.

• χαμηλόφωνα = softly / in a low voice
• καθαρά = clearly

They both modify the verb μιλάει.

So the structure is:

• μιλάει χαμηλόφωνα = she speaks softly
• μιλάει καθαρά = she speaks clearly

Because adverbs do not agree with the subject in gender or number.

Even though the subject is feminine, the adverbs stay the same:

• μιλάει χαμηλόφωνα
• μιλάει καθαρά

This is similar to English. We do not change softly or clearly depending on whether the speaker is a man or a woman.

Because πολύ here is an adverb meaning very, not an adjective.

It modifies another adverb, καθαρά:

• πολύ καθαρά = very clearly

When πολύ works as an adverb, it stays πολύ.

Compare:

• πολύ καθαρά = very clearly
• πολύ μιλάει = he/she talks a lot

But when you want much/many as an adjective, it changes:

• πολλή δουλειά = a lot of work
• πολλοί άνθρωποι = many people

So in this sentence, πολύ is unchanged because it means very.

Here it means new in the sense of a new colleague, so someone who is new in the workplace or new to the speaker.

With people, καινούριος / καινούρια does not mean newly manufactured, of course. It means someone recently added, recently met, or recently joined.

In English, we naturally understand my new colleague the same way, and Greek works similarly here.

In μιλάει, the ending is really -ει attached to μιλά-, so learners should think of it as:

• μι-λά-ει

In careful pronunciation, it is often heard as three syllables, roughly mi-LA-i.

So this is not the usual simple αι = e situation. The vowels belong to different parts of the word, and the result sounds different from a normal αι digraph inside a single unit.

That is one reason some learners find μιλά easier at first.

Because αλλά means but, and the comma marks a contrast between two ideas:

• she speaks softly
• but very clearly

So:

• μιλάει χαμηλόφωνα, αλλά πολύ καθαρά

This is very similar to normal English punctuation before but. In standard Greek writing, the comma here is natural and expected.