Η καινούρια καθηγήτρια μου έκανε πολύ καλή εντύπωση, γιατί εξηγεί τα πάντα αργά.

Because all three words have to agree with each other in gender, number, and case.

• η = the (feminine singular nominative)
• καινούρια = new (feminine singular nominative)
• καθηγήτρια = teacher (feminine singular nominative)

The noun καθηγήτρια is feminine, so the article and adjective must also be feminine.

You could think of it as:

• masculine: ο καινούριος καθηγητής
• feminine: η καινούρια καθηγήτρια
• neuter: το καινούριο βιβλίο

So καινούρια is simply the feminine form that matches καθηγήτρια.

Here μου means to me.

In this sentence, μου έκανε πολύ καλή εντύπωση literally means something like:

she made a very good impression on me

So μου is not showing possession here. It is an indirect object clitic.

Compare:

• η καθηγήτριά μου = my teacher
  Here μου means my
• η καθηγήτρια μου έκανε εντύπωση = the teacher impressed me / made an impression on me
  Here μου means to me

Greek uses the same form μου for both ideas, so context matters.

Because Greek object clitics normally come before the verb.

So:

• μου έκανε εντύπωση
• σου είπε
• μας εξήγησε

This is the normal position in statements.

In some other structures, clitics can appear after the verb, especially with imperatives, for example:

• πες μου = tell me

But in a sentence like this one, μου έκανε is exactly what you would expect.

Έκανε is the aorist (simple past) of κάνω.

Here it refers to a completed event in the past:

• μου έκανε πολύ καλή εντύπωση = she made a very good impression on me

The idea is that the speaker had an impression at a particular moment or in a particular encounter.

A rough contrast:

• έκανε εντύπωση = made an impression / impressed
• έκανε is a completed past action

So the sentence is describing:

1. a past reaction: she impressed me
2. the reason for that impression: because she explains everything slowly

Yes. Κάνω εντύπωση is a very common Greek expression.

It means:

• to make an impression
• sometimes to impress
• sometimes to stand out, depending on context

So:

• Μου έκανε εντύπωση. = It impressed me / It struck me.
• Μου έκανε καλή εντύπωση. = It made a good impression on me.
• Μου έκανε πολύ καλή εντύπωση. = It made a very good impression on me.

This is a very natural Greek way to express the idea.

Because πολύ here means very, and it modifies the adjective καλή.

So:

• πολύ καλή εντύπωση = a very good impression

Important distinction:

• πολύ can mean very before an adjective or adverb
• πολύς / πολλή / πολύ can also mean much / many, but then it changes form like an adjective

Here it is the adverb πολύ = very, so it does not change.

Compare:

• πολύ καλή = very good
• πολύ αργά = very slowly / very late, depending on context
• πολλή δουλειά = a lot of work

And καλά would be wrong here because καλά is not the feminine singular adjective needed before εντύπωση. The noun εντύπωση is feminine singular, so the adjective must be καλή.

Because the speaker is giving a reason that is presented as generally true or characteristic now.

So the sentence means something like:

• The new teacher made a very good impression on me because she explains everything slowly.

The past action is:

• μου έκανε πολύ καλή εντύπωση = she made a very good impression on me

The reason is stated as a present/general fact about her teaching style:

• γιατί εξηγεί τα πάντα αργά = because she explains everything slowly

This is very natural in both Greek and English. It suggests that explaining slowly is her usual way of teaching, not just something that happened once.

If you wanted to focus on one past occasion, you might expect a past form instead.

Yes. Γιατί can mean both:

• because
• why

Here it clearly means because, since it introduces the reason:

• ..., γιατί εξηγεί τα πάντα αργά.
• ..., because she explains everything slowly.

Compare:

• Γιατί άργησες; = Why were you late?
• Άργησα γιατί είχε κίνηση. = I was late because there was traffic.

So you have to tell from the context whether it means why or because.

Τα πάντα means everything.

Literally, it is built from the plural idea of all things:

• τα = the (neuter plural)
• πάντα = all / everything in this expression

So Greek often uses a plural-looking structure where English uses singular everything.

Examples:

• Ξέρει τα πάντα. = He/She knows everything.
• Εξηγεί τα πάντα αργά. = She explains everything slowly.

A learner might expect όλα, and that can also work in some contexts, but τα πάντα is a very common fixed expression for everything.

Because αργά is an adverb, and it describes how she explains.

• εξηγεί αργά = she explains slowly

By contrast:

• αργός = slow (masculine adjective)
• αργή = slow (feminine adjective)
• αργό = slow (neuter adjective)

Adjectives describe nouns:

• ο αργός μαθητής = the slow male student
• η αργή διαδικασία = the slow process

Adverbs describe verbs:

• μιλάει αργά = he/she speaks slowly
• εξηγεί αργά = he/she explains slowly

So αργά is the correct form because it modifies the verb εξηγεί.

More or less, yes—that is close to the Greek structure.

A very literal breakdown would be:

• Η = the
• καινούρια = new
• καθηγήτρια = teacher
• μου = to me
• έκανε = made
• πολύ καλή εντύπωση = very good impression
• γιατί = because
• εξηγεί = explains
• τα πάντα = everything
• αργά = slowly

But in natural English, you would say:

• The new teacher made a very good impression on me, because she explains everything slowly.

The literal version is useful for seeing how Greek is built, but it is not how natural English would normally phrase it.

Yes. Καινούρια and καινούργια are both common forms.

Likewise:

• καινούριος / καινούργιος
• καινούρια / καινούργια
• καινούριο / καινούργιο

They both mean new. In everyday Greek, both are widely understood and used. The difference is mainly one of form and usage preference, not meaning.

So if you see η καινούργια καθηγήτρια, it means exactly the same thing as η καινούρια καθηγήτρια.

Greek word order is more flexible than English, but not completely free.

This sentence uses a very natural, neutral order:

• Η καινούρια καθηγήτρια μου έκανε πολύ καλή εντύπωση...

That said, Greek can move elements for emphasis. For example, you might hear different arrangements in real speech, especially with emphasis on μου, πολύ καλή εντύπωση, or the subject.

Still, some parts are less flexible than others:

• the article and noun stay closely connected
• the adjective usually stays near the noun
• the clitic μου normally appears before the finite verb in a statement

So yes, Greek allows flexibility, but this version is the standard, unmarked way to say it.