Mi padre dice que ser ambicioso no es un defecto, siempre que también seas generosa con tu tiempo.

Here que means that and introduces the next clause:

Mi padre dice que... = My father says that...

In English, that is often optional, but in Spanish que is normally kept.

Spanish often leaves out subject pronouns because the verb ending already shows who the subject is.

Seas is the tú form of the present subjunctive of ser, so tú is understood automatically.

So:

...siempre que también seas generosa...
means
...as long as you are also generous...

Adding tú would only be for extra emphasis or contrast.

Spanish often uses an infinitive as a noun-like idea.

So ser ambicioso means being ambitious or to be ambitious in a general sense.

This whole infinitive phrase acts as the subject of the sentence:

Ser ambicioso no es un defecto = Being ambitious is not a flaw

This is very common in Spanish:

• Fumar es malo = Smoking is bad
• Viajar es caro = Travelling is expensive

Because ambicioso is being treated as a personal quality or characteristic, not a temporary state.

• ser ambicioso = to be ambitious as a trait
• estar is normally used for temporary conditions, location, or results

So ser is the natural choice here.

This is a very natural question.

Generosa clearly refers to a female you, so it must agree in gender:

• generosa for a woman
• generoso for a man

In ser ambicioso, the phrase is more general: being ambitious as an idea. In that kind of generic expression, Spanish often uses the masculine singular as the default form.

That said, if the sentence is clearly addressed to a woman, many speakers would also find ser ambiciosa natural.

So:

• ser ambicioso = generic/general wording
• seas generosa = specifically addressing a woman

Because in Spanish, when you classify something as a member of a category, you normally use the article.

So:

• es un defecto = it is a flaw
• no es un defecto = it is not a flaw

Leaving out un here would sound unnatural.

Here siempre que means as long as, provided that, or so long as.

So:

...siempre que también seas generosa con tu tiempo
= ...as long as you are also generous with your time

Be careful: siempre que can also mean whenever in other contexts. The meaning depends on the grammar and situation.

Because siempre que is introducing a condition, and Spanish normally uses the subjunctive after it in this meaning.

So:

• siempre que seas... = as long as you are...
• not siempre que eres... in this sentence

The subjunctive is used because this is a condition or requirement, not a simple statement of fact.

A useful pattern is:

siempre que + subjunctive = provided that / as long as

También means also or too.

It shows that being generous with your time is an additional requirement, not the main point by itself.

So the idea is:

Being ambitious is not a flaw, as long as you are also generous with your time.

Without también, the sentence would still make sense, but it would lose that idea of in addition.

It means generous with your time.

In other words, willing to give time, attention, or help to other people instead of keeping all your time for yourself.

The preposition con is the natural one in this expression:

• ser generoso con algo
• ser generosa con tu tiempo

So this is not a word-for-word logic you need to invent each time; it is a set phrase you can learn as a chunk.

Because tu here is a possessive adjective meaning your.

• tu = your
• tú = you

So:

• tu tiempo = your time
• tú seas generosa = you are generous would use tú if the pronoun were written

This accent difference is very important in Spanish.

It can be either, depending on context.

Often ambicioso is neutral or positive, especially when talking about goals, work, or personal drive. But it can sound negative if it suggests being selfish, ruthless, or wanting too much.

This sentence makes the intended nuance clear: being ambitious is not a flaw, as long as you are also generous with your time

So the speaker accepts ambition, but only if it is balanced with generosity.