Quando estou a conduzir, só faço uma ultrapassagem quando vejo bem a estrada.

In European Portuguese, estar a + infinitive is a very common way to express an action in progress, like English to be driving.

So:

• estou a conduzir = I am driving
• conduzo = I drive / I am driving depending on context

In this sentence, Quando estou a conduzir emphasizes the idea of while I’m in the act of driving.

A simpler present tense version is also possible:

• Quando conduzo, ...

That sounds more like when I drive / whenever I drive, while quando estou a conduzir feels more clearly connected to the ongoing situation.

That a is part of the European Portuguese progressive construction:

• estar a + infinitive

Examples:

• estou a comer = I am eating
• estás a estudar = you are studying
• estamos a falar = we are talking

This is one of the big differences between European and Brazilian Portuguese. In Brazil, you are much more likely to hear:

• estou dirigindo
• estou falando

But in Portugal, estou a conduzir and estou a falar are the normal forms.

Só means only here, and its position shows what it is limiting.

• só faço uma ultrapassagem = I only make an overtake / I only overtake

It limits the action faço.

Portuguese often places só directly before the verb:

• Só vou amanhã = I’m only going tomorrow
• Só quero descansar = I only want to rest

You could sometimes move só, but the most natural position here is exactly the one in the sentence.

Both are possible, but they are not equally natural in all contexts.

• faço uma ultrapassagem = literally I do/make an overtaking manoeuvre
• ultrapasso = I overtake

The noun ultrapassagem is very common in driving language, especially when talking about a specific manoeuvre. It can sound slightly more technical or precise.

So this sentence focuses on the act as a manoeuvre:

• só faço uma ultrapassagem quando...

A more direct verbal version would be:

• só ultrapasso quando vejo bem a estrada

That is also correct and natural.

Ultrapassagem is a noun, not a verb. It means overtaking or an overtaking manoeuvre.

It comes from the verb:

• ultrapassar = to overtake / to pass

So:

• uma ultrapassagem = an overtaking manoeuvre
• fazer uma ultrapassagem = to perform an overtaking manoeuvre

This noun is feminine, which is why it takes:

• uma ultrapassagem

Because the sentence has two time clauses:

1. Quando estou a conduzir = when I’m driving
2. quando vejo bem a estrada = when I can clearly see the road

The first sets the general situation. The second gives the condition for the overtaking.

In English, repeating when is also possible:

• When I’m driving, I only overtake when I can see the road clearly.

So the Portuguese repetition is completely normal.

Here bem means something like well, clearly, or properly.

So:

• vejo bem a estrada = I can see the road clearly / I see the road well

It modifies the verb vejo.

This is a common Portuguese structure:

• ouço bem = I hear well / clearly
• não vejo bem = I can’t see well
• percebo bem = I understand clearly

In this sentence, bem suggests good visibility, which is important in the context of overtaking.

Portuguese uses the definite article much more often than English.

So where English might say:

• I can see the road clearly

Portuguese naturally says:

• vejo bem a estrada

The article a is normal here because we are talking about the road ahead / the road in that driving situation, not just the general idea of roadness.

Compare:

• Vejo a casa = I see the house
• Vejo o mar = I see the sea
• Vejo a estrada = I see the road

Yes, you could say:

• Quando eu estou a conduzir, só faço uma ultrapassagem quando vejo bem a estrada.

But in Portuguese, subject pronouns are often omitted because the verb ending already shows the person:

• estou
• faço
• vejo

All clearly indicate I.

Adding eu usually gives extra emphasis or contrast, for example:

• Eu só faço uma ultrapassagem quando vejo bem a estrada, mas ele arrisca mais.

So in the original sentence, leaving out eu is the most natural choice.

Yes, conduzir is very common in European Portuguese for to drive a vehicle.

You may also see or hear:

• guiar = to drive
• dirigir = to direct / to drive, though this is less everyday in Portugal than conduzir

For Portugal, conduzir fits very naturally in a road-safety sentence like this one.

Examples:

• Se conduzires com cuidado, chegas bem. = If you drive carefully, you’ll arrive safely.
• Ele está a conduzir. = He is driving.

Yes. A few natural alternatives are:

• Quando conduzo, só ultrapasso quando vejo bem a estrada.
• Quando estou a conduzir, só ultrapasso quando vejo bem a estrada.
• Quando conduzo, só faço ultrapassagens quando vejo bem a estrada.

These versions are all grammatical, but they differ slightly:

• conduzo is a bit simpler and less explicitly progressive than estou a conduzir
• ultrapasso uses the verb directly
• faço uma ultrapassagem highlights the manoeuvre as a noun phrase
• faço ultrapassagens sounds more general or habitual than faço uma ultrapassagem

The original sentence is perfectly natural and very clear, especially in a careful, instructional context.