Η φίλη μου λέει ότι δεν είναι μόνο τύχη, είναι και προσπάθεια.

Η φίλη μου means my friend when the friend is female.

• η = the for a feminine singular noun
• φίλη = female friend
• μου = my

So literally it is the friend my, but natural English is my friend.

Greek often uses the definite article where English would not, so η φίλη μου is the normal way to say my friend.

In Greek, possessive forms like μου often come after the noun:

• η φίλη μου = my friend
• το βιβλίο μου = my book
• ο αδερφός μου = my brother

This is one of the most basic Greek patterns. English says my friend, but Greek usually says the friend my.

Λέει is the 3rd person singular present of λέω, meaning to say or to tell.

So:

• λέω = I say
• λες = you say
• λέει = he/she/it says

Here it matches η φίλη μου, so:

• Η φίλη μου λέει = My friend says

Ότι means that and introduces a subordinate clause:

• Η φίλη μου λέει ότι... = My friend says that...

In English, that is sometimes omitted:

• My friend says that...
• My friend says...

Greek can also sometimes omit ότι in speech, but using it is very normal and clear.

Δεν is the standard negation used before verbs, and είναι means is.

So:

• είναι = is
• δεν είναι = is not

This part means it is not.

Greek does not usually need an explicit subject like it here, because the meaning is understood from context.

Μόνο means only.

So:

• δεν είναι μόνο τύχη = it isn’t only luck

The word μόνο is placed before the thing being limited, just like English only often is.

Here it sets up a contrast:

• not only luck
• also effort

Yes, Greek could sometimes omit repeated words, but repeating είναι here is very natural and clear:

• δεν είναι μόνο τύχη, είναι και προσπάθεια

Literally:

• it is not only luck, it is also effort

Repeating είναι gives the sentence balance and emphasis. It sounds deliberate: not just one thing, but another thing too.

Here και means also / too, not just simple and.

So:

• είναι και προσπάθεια = it is also effort

This pairs nicely with μόνο:

• όχι/δεν μόνο ... και ...
• not only ... also ...

In this sentence, και highlights the second part of the idea: luck is part of it, but effort matters too.

That is a very good question, because English learners often expect a direct match.

Greek could also say:

• δεν είναι μόνο τύχη αλλά και προσπάθεια

That would mean:

• it’s not only luck but also effort

Your sentence says:

• δεν είναι μόνο τύχη, είναι και προσπάθεια

This is slightly more split into two clauses:

• it’s not only luck, it’s also effort

So the original sentence is perfectly natural. It is just a slightly different structure from the fixed English pattern not only..., but also....

In this sentence, τύχη and προσπάθεια are used as predicate nouns after είναι, and Greek often leaves out the article in this kind of structure.

So:

• είναι τύχη = it is luck
• είναι προσπάθεια = it is effort

Using no article makes them sound more like general concepts or qualities.

If you added an article, the nuance could change depending on context. Here, the article-less form is the natural one for a general statement.

Both are in the nominative singular.

• τύχη = luck
• προσπάθεια = effort

They are feminine nouns, and here they function as predicate nouns after είναι.

A useful point for learners: after είμαι (to be), Greek normally uses the nominative, just as English uses a basic noun form in sentences like it is luck or it is effort.

Yes. Greek very often omits subject pronouns when they are not needed.

In English, you need:

• it is not only luck, it is also effort

In Greek, the verb form and context are enough:

• δεν είναι μόνο τύχη, είναι και προσπάθεια

There is no separate word for it, but the meaning is understood.

A very literal breakdown would be:

• Η = the
• φίλη = friend
• μου = my
• λέει = says
• ότι = that
• δεν = not
• είναι = is
• μόνο = only
• τύχη = luck
• είναι = is
• και = also
• προσπάθεια = effort

So a near-literal version is:

The friend my says that not is only luck, is also effort.

Of course, natural English is:

My friend says that it’s not only luck, it’s also effort.

Yes, φίλη can sometimes mean female friend or girlfriend, depending on context.

By itself:

• η φίλη μου can mean my female friend
• in some contexts it can also mean my girlfriend

Usually the situation makes it clear. If the intended meaning is simply female friend, this sentence is completely normal.