Πατάω το φρένο όταν βλέπω πεζό στη διάβαση.

Greek often leaves out subject pronouns because the verb ending already shows the person.

• πατάω = I press / I hit
• βλέπω = I see

So εγώ is not needed unless you want emphasis or contrast:

• Εγώ πατάω το φρένο... = I press the brake...

Literally, it means I press the brake. In normal driving English, that is usually I hit the brake, I apply the brakes, or simply I brake.

It is a very natural Greek way to express the action of braking. By itself, it does not necessarily mean an emergency stop; it just means pressing the brake.

Yes. They are two standard forms of the same verb.

• πατάω is very common in everyday speech
• πατώ is a shorter form, also correct

So you may hear both:

• Πατάω το φρένο
• Πατώ το φρένο

Both mean the same thing here.

Greek uses the definite article more often than English does. Here το φρένο refers to the brake of the vehicle, a specific and understood thing in the situation.

So even if English might sometimes just say I brake, Greek naturally says I press the brake with the article:

• το φρένο

Because φρένο is a neuter noun, and in Modern Greek many neuter nouns have the same form in the nominative and the accusative singular.

So:

• nominative: το φρένο
• accusative: το φρένο

Even though it is the direct object of πατάω, the form stays the same.

Because this sentence describes a general habit or usual rule:

• When I see a pedestrian in the crosswalk, I press the brake.

Greek uses the present tense for that kind of repeated or habitual meaning.

If you were talking about one future occasion, Greek would normally use a different form:

• Όταν δω πεζό στη διάβαση, θα πατήσω το φρένο.
• When I see a pedestrian in the crosswalk, I will press the brake.

So βλέπω here shows repeated, habitual action.

Because πεζό is the accusative singular form, and it is the direct object of βλέπω.

• πεζός = nominative, the basic dictionary form
• πεζό = accusative, used here after βλέπω

Compare:

• Ο πεζός περπατάει. = The pedestrian is walking.
• Βλέπω πεζό. = I see a pedestrian.

Greek can leave an indefinite noun without an article, especially in sentences like this.

So:

• βλέπω πεζό = I see a pedestrian

You can also say:

• βλέπω έναν πεζό

That is also correct, and it makes the indefiniteness more explicit. But the version without έναν is very natural.

Originally, πεζός is an adjective meaning on foot. But in Greek, adjectives are often used as nouns when the meaning is clear.

So here:

• πεζός = pedestrian

This is very common in traffic language.

στη is the usual contracted form of σε τη.

So:

• σε + τη διάβαση → στη διάβαση

It means in / at / on the crosswalk, depending on natural English wording.

In Modern Greek, location is commonly expressed with σε + accusative, so στη διάβαση is completely normal.

Literally, διάβαση means crossing or passage. In road and traffic context, it often stands for:

• διάβαση πεζών = pedestrian crossing / crosswalk

So in this sentence, στη διάβαση naturally means in the crosswalk or at the crossing.

Yes. Greek word order is fairly flexible.

You can say:

• Πατάω το φρένο όταν βλέπω πεζό στη διάβαση.
• Όταν βλέπω πεζό στη διάβαση, πατάω το φρένο.

Both are natural. The difference is mainly one of emphasis and flow, not basic meaning.