Η αγωνία της μαμάς μου φεύγει όταν της τηλεφωνώ.

Yes:

• Η = the
• αγωνία = anxiety, worry, anguish
• της μαμάς μου = of my mom / my mom’s
• φεύγει = leaves, goes away
• όταν = when / whenever
• της = to her
• τηλεφωνώ = I call / I phone

A very literal version would be:

• The anxiety of my mom goes away when I phone her.

Natural English would usually be something like:

• My mom’s anxiety goes away when I call her.
• My mom stops worrying when I call her.

Because Greek often shows possession with the genitive.

Here is the pattern:

• η μαμά μου = my mom
• της μαμάς μου = of my mom / my mom’s

So:

• Η αγωνία της μαμάς μου
  literally = the anxiety of my mom

That is how Greek naturally builds my mom’s anxiety.

A useful thing to notice:

• μαμά is the basic form
• μαμάς is the genitive singular form after της

So της μαμάς μου is not random; it is the normal possessive structure.

Greek uses the definite article much more often than English does.

So Η αγωνία is completely normal Greek. Even with abstract nouns like worry or anxiety, Greek often keeps the article where English might not.

Here it marks αγωνία as the subject:

• Η αγωνία ... φεύγει = The anxiety ... goes away

In English, depending on style, you might say:

• My mom’s anxiety goes away
• The anxiety my mom feels goes away

Greek strongly prefers the article here.

Αγωνία can mean several related things, depending on context:

• anxiety
• worry
• anguish
• nervous suspense
• distress

In this sentence, it most naturally means something like:

• worry
• anxiety

So the idea is that the mother feels worried, and that feeling disappears when the speaker calls her.

In everyday translation, worry is often the most natural choice.

The basic meaning of φεύγω is leave or go away.

But Greek often uses it with things like feelings, problems, pain, fear, etc. In those cases it means:

• go away
• disappear
• pass

So:

• Η αγωνία φεύγει = The anxiety goes away
• more naturally: The worry disappears

It is the same basic idea as in English when we say:

• The pain went away
• The fear left her

Yes, here της means to her.

That is because τηλεφωνώ works with an indirect-object-style pronoun:

• Της τηλεφωνώ = I call her / I phone her
• literally: I phone to her

With a full noun, Greek often uses σε:

• Τηλεφωνώ στη μαμά μου = I call my mom

But with a weak pronoun, Greek uses the clitic form:

• της = to her

So in this sentence:

• όταν της τηλεφωνώ = when I call her

Important: της can also mean of the or her in other contexts, but here, because it stands right before the verb, it is the object pronoun to her.

Because Greek often drops subject pronouns when they are already clear from the verb ending.

• τηλεφωνώ already means I call / I am calling

So Greek does not need εγώ unless you want emphasis or contrast.

For example:

• Της τηλεφωνώ. = I call her.
• Εγώ της τηλεφωνώ, όχι ο αδερφός μου. = I’m the one who calls her, not my brother.

This is very common in Greek.

Here it can mean either, but in context whenever is often the best way to understand it.

Because the verb is in the present and the sentence describes a repeated or general situation, the sense is:

• My mom’s anxiety goes away whenever I call her.

English may still use when, but the idea is habitual, not necessarily one single event.

So:

• όταν της τηλεφωνώ = when I call her / whenever I call her

Because the sentence describes a general repeated action.

• τηλεφωνώ = I call / I am calling
• after όταν, this gives a habitual meaning: when/whenever I call

If you were talking about a single future event, Greek would often use a different form, for example:

• όταν της τηλεφωνήσω = when I call her (on a specific future occasion)

So:

• όταν της τηλεφωνώ = repeated/general
• όταν της τηλεφωνήσω = one future instance

This is an important Greek aspect distinction.

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

The original sentence is neutral and natural:

• Η αγωνία της μαμάς μου φεύγει όταν της τηλεφωνώ.

But you could also say:

• Όταν της τηλεφωνώ, η αγωνία της μαμάς μου φεύγει.

That means basically the same thing. The difference is mainly one of focus or rhythm, not core meaning.

One thing that usually stays stable is the clitic pronoun:

• της normally comes right before the verb: της τηλεφωνώ

Yes. μαμά is the everyday, affectionate word for mom / mum.

So this sentence sounds natural and personal.

A more formal or neutral word would be:

• μητέρα = mother

Then the phrase would become:

• Η αγωνία της μητέρας μου φεύγει όταν της τηλεφωνώ.

That is correct, but it sounds more formal and less warm than μαμά.

So:

• μαμά = everyday, familiar
• μητέρα = more formal, more written, more distant in tone