Όταν βλέπω το βιβλίο στο πάτωμα, το σηκώνω και το βάζω στο τραπέζι.

Όταν introduces a time clause, so it means when or whenever.

In this sentence, Όταν βλέπω το βιβλίο στο πάτωμα means when/whenever I see the book on the floor.

It is different from αν, which means if and introduces a condition, not a time.

• Όταν βλέπω... = When I see...
• Αν δω... = If I see...

So όταν is about time, while αν is about possibility or condition.

Greek uses the present tense here because the sentence describes a habitual or repeated action:

• βλέπω = I see
• σηκώνω = I pick up / lift
• βάζω = I put

So the sense is not one single event, but something like Whenever this happens, this is what I do.

If you wanted a one-time future meaning, Greek would usually change the structure. For example:

• Όταν δω το βιβλίο στο πάτωμα, θα το σηκώσω και θα το βάλω στο τραπέζι.

That means When I see the book on the floor, I will pick it up and put it on the table.

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

Here, the ending -ω tells you the subject is I:

• βλέπω = I see
• σηκώνω = I lift / pick up
• βάζω = I put

So εγώ is not necessary. You would only add εγώ for emphasis or contrast:

• Εγώ το σηκώνω, όχι αυτός.
  I pick it up, not him.

Yes. All three are first-person singular present active forms, meaning I see, I pick up, and I put.

The ending -ω is a very common marker of I in Modern Greek verbs.

So a learner can recognize that the same subject is doing all three actions.

Το βιβλίο means the book. Greek uses the definite article very regularly, just like English uses the.

Here the speaker is referring to a specific book, not just any book, so το is natural.

Also, in Greek, articles are strongly tied to the noun’s gender, number, and case. Since βιβλίο is a neuter singular noun, its article here is το.

Yes. In this sentence, το βιβλίο is the direct object of βλέπω, so it is in the accusative.

But βιβλίο is a neuter singular noun, and in Modern Greek the nominative and accusative are often identical for neuter singular nouns.

So:

• nominative: το βιβλίο
• accusative: το βιβλίο

The form stays the same, and you understand its role from the sentence structure and the verb.

Because στο is the normal contraction of σε + το.

So:

• σε το πάτωμα → στο πάτωμα
• σε το τραπέζι → στο τραπέζι

This contraction is extremely common in Modern Greek and is the form you would normally use.

Similar contractions include:

• στη = σε + τη
• στον = σε + τον

It can correspond to different English prepositions depending on the context.

The Greek preposition σε is broader than any one English preposition. It can express:

• location: in / at / on
• direction: to / into / onto

So here:

• στο πάτωμα = on the floor
• στο τραπέζι = on the table

With βάζω, there is also a sense of movement toward a place, so English naturally says put it on the table.

In other words, Greek uses σε, but English chooses the most natural preposition for the situation.

That το is not the article the. It is the object pronoun it.

First, the noun is mentioned:

• το βιβλίο = the book

Then the sentence refers back to it with the pronoun:

• το σηκώνω = I pick it up
• το βάζω = I put it

Greek does this very naturally. Once the object has been introduced, a short pronoun is used to continue referring to it.

Because in Modern Greek, unstressed object pronouns usually come before a finite verb.

So Greek says:

• το σηκώνω
• το βάζω

not the equivalent of σηκώνω το in normal word order.

This is a very important pattern to get used to:

• τον βλέπω = I see him
• την ξέρω = I know her
• το θέλω = I want it

A big exception is with affirmative imperatives, where the pronoun usually comes after:

• Σήκωσέ το = Pick it up
• Βάλ’ το / Βάλτο = Put it

Here σηκώνω means pick up or lift.

Its basic idea is raise or lift upward, so it fits very naturally when something is on the floor and you lift it.

Depending on context, σηκώνω can also mean things like:

• lift
• raise
• pick up
• get up

But in this sentence, because the object is the book on the floor, the meaning pick up is the most natural one.

Because the sentence begins with a subordinate clause introduced by Όταν:

• Όταν βλέπω το βιβλίο στο πάτωμα, ...

Then the main clause follows:

• το σηκώνω και το βάζω στο τραπέζι.

This is very similar to English punctuation:

• When I see the book on the floor, I pick it up and put it on the table.

So the comma helps separate the when-clause from the main statement.

Because και simply joins the two actions done by the same subject:

• το σηκώνω και το βάζω στο τραπέζι

This works just like English and.

Greek does not need to repeat the subject, because the verb forms already show that the same person is acting. So the structure is compact and natural:

• I pick it up and put it on the table

Yes, that is possible.

You could also say:

• Το σηκώνω και το βάζω στο τραπέζι όταν βλέπω το βιβλίο στο πάτωμα.

This is grammatically fine, but it changes the rhythm and emphasis. The original version starts with the time condition, so it sets the scene first:

• When I see the book on the floor, ...

That is often the more natural choice when the speaker wants to highlight the circumstance before the action.

In this sentence, whenever is often the better way to understand it, even though when is also a correct translation.

That is because the present tense gives the sentence a general, repeated sense:

• Whenever I see the book on the floor, I pick it up and put it on the table.

So in Greek, όταν + present often has that habitual meaning in context.