Όταν σκίζω κατά λάθος τη σακούλα με το χώμα, το μαζεύω αμέσως από το πάτωμα.

Here Όταν means when or whenever.

Because the sentence uses present-tense verbs, it sounds like a general/habitual situation:

• Όταν σκίζω..., το μαζεύω... = When/Whenever I tear..., I pick it up...

So this is not necessarily talking about one single event right now; it can describe what the speaker typically does in that situation.

In Greek, the present tense is often used for habitual or repeated actions, just like in English:

• When I accidentally tear the bag, I immediately pick it up...

That does not mean the speaker is tearing it at this exact moment. It means this is what I do when that happens.

So:

• σκίζω = I tear / I rip
• μαζεύω = I gather up / collect

Both are present because the sentence describes a regular reaction.

Yes, but it would change the meaning.

• Όταν σκίζω ... το μαζεύω ... = Whenever I tear ..., I pick it up ...
  → habitual / repeated situation

• Όταν σκίσω ... θα το μαζέψω ... = When I tear it ..., I’ll pick it up ...
  → one future event

So σκίζω here is chosen because the sentence is describing a general pattern, not one specific future occurrence.

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

• σκίζω = I tear
• μαζεύω = I collect

So εγώ is unnecessary unless you want emphasis or contrast:

• Εγώ το μαζεύω αμέσως, όχι αυτός.
  I pick it up immediately, not him.

This is very normal in Greek.

Because σακούλα is the direct object of σκίζω.

Dictionary form:

• η σακούλα = the bag → nominative

Direct object form:

• τη(ν) σακούλα = the bag → accusative

So after σκίζω (I tear), you need the accusative:

• σκίζω τη σακούλα = I tear the bag

Both are possible in principle, but τη σακούλα is the normal form here.

The full accusative article is την, but the final -ν is often dropped before some consonants in everyday Greek. Since σακούλα begins with σ, you commonly get:

• τη σακούλα

Before vowels and certain consonants, the -ν is usually kept:

• την πόρτα
• την ώρα

So τη σακούλα is completely natural.

κατά λάθος is a fixed expression meaning:

• by mistake
• accidentally

You can learn it as a chunk.

Examples:

• Το έκανα κατά λάθος. = I did it by mistake.
• Έσπασα το ποτήρι κατά λάθος. = I broke the glass accidentally.

In your sentence, it tells you that the tearing is not intentional.

Yes. It contains:

• κατά = a preposition
• λάθος = mistake/error

But for a learner, the important thing is to treat κατά λάθος as a set phrase meaning accidentally.

You do not usually translate it word-for-word in normal use; you just recognize it as one expression.

Literally, yes: με το χώμα = with the soil/dirt.

But in this sentence it describes which bag we mean:

• τη σακούλα με το χώμα = the bag with the soil in it

In natural English, you might also say:

• the bag of soil
• the soil bag
  depending on context

So με is literally with, but the whole phrase functions like a description of the bag’s contents.

Yes, that is also possible.

Compare:

• σακούλα με το χώμα = the bag with the soil in it
• σακούλα χώματος = bag of soil

Both can work, but they are phrased a little differently. The version with με is very transparent and conversational: it identifies the bag by saying what is in it.

It refers to το χώμα.

• χώμα is neuter singular
• the matching object pronoun is το

So:

• το μαζεύω = I gather it up / I collect it

Even though in English you may imagine bits of spilled dirt, Greek treats χώμα as a mass noun, so singular το is perfectly natural.

Because Greek weak object pronouns normally come before a finite verb.

So Greek says:

• το μαζεύω

not:

• μαζεύω το ❌

This is one of the most important word-order patterns to get used to in Greek.

A few very common examples:

• Το βλέπω. = I see it.
• Την ξέρω. = I know her.
• Τα θέλω. = I want them.

Yes, and that is exactly why it works well here.

μαζεύω often means:

• gather
• collect
• pick up
• clean up

When something like soil, rice, papers, or trash is scattered around, μαζεύω is very natural:

• μαζεύω το χώμα
• μαζεύω τα χαρτιά
• μαζεύω τα σπασμένα

So although English may say pick it up, Greek often prefers μαζεύω for the idea of collecting spilled or scattered material.

από means from or off.

So:

• από το πάτωμα = from the floor / off the floor

That fits the idea that the soil has fallen there, and the speaker is collecting it from that surface.

It is in the accusative, because modern Greek uses the accusative after από.

The noun is neuter:

• nominative: το πάτωμα
• accusative: το πάτωμα

So it looks the same in both cases. That is why English speakers sometimes do not notice a case change here.

αμέσως means immediately / right away.

Its position is quite natural here:

• το μαζεύω αμέσως

This puts the focus first on the action (I collect it) and then adds immediately.

Greek word order is flexible, so other positions are possible for emphasis, for example:

• Αμέσως το μαζεύω.
• Το μαζεύω αμέσως από το πάτωμα.

But the version in the sentence sounds very normal.

No, not completely. Greek has fairly flexible word order, especially because case endings and articles help show grammatical roles.

This order is natural:

• Όταν σκίζω κατά λάθος τη σακούλα με το χώμα, το μαζεύω αμέσως από το πάτωμα.

But Greek can move parts around for emphasis. For example:

• Το μαζεύω αμέσως από το πάτωμα όταν σκίζω κατά λάθος τη σακούλα με το χώμα.

That said, the original version is smoother and more neutral.

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

• Όταν σκίζω κατά λάθος τη σακούλα με το χώμα, ...

Then the main clause follows:

• το μαζεύω αμέσως από το πάτωμα.

Greek punctuation here works much like English: when the when-clause comes first, it is normally separated by a comma from the main clause.