Η μαμά μου μπορεί να έχει βάλει τη μαξιλαροθήκη στο πλυντήριο, γιατί δεν είναι πια στο κρεβάτι.

Greek usually keeps the definite article with nouns, even when there is a possessive like μου.

So:

• η μαμά μου = my mom
• το σπίτι μου = my house

To an English speaker, this may feel like the my mom, but in Greek it is completely normal and natural.
You can sometimes hear μαμά μου without the article, but that is often more like direct address or a more emotional/exclamatory use, not the neutral pattern used here.

In Greek, weak possessive forms such as μου, σου, του, της usually come after the noun.

So:

• η μαμά μου = my mom
• ο αδερφός της = her brother
• το βιβλίο σου = your book

μου is not a separate stressed word like English my. It is a short clitic form, so it normally follows the noun.

Yes, μαμά is the everyday word for mom / mum. It sounds natural and conversational.

• μαμά = everyday, warm, normal spoken Greek
• μητέρα = more formal, official, or written, like mother

In this sentence, μαμά fits better because the whole sentence sounds like ordinary speech.

μπορώ / μπορεί can express both:

• ability: can
• possibility: may / might

Here it shows possibility, not ability.

So:

• Η μαμά μου μπορεί να έχει βάλει...
  = My mom may have put... / might have put...

The context makes it clear that the speaker is guessing what probably happened.

Because Greek normally uses να + verb where English often uses an infinitive.

So Greek says:

• μπορεί να βάλει = she may put / she can put
• μπορεί να έχει βάλει = she may have put

English uses to put or have put, but Modern Greek does not use an infinitive in this kind of structure. Instead, it uses να plus the verb form.

This whole phrase works together:

• μπορεί να = may / might
• έχει βάλει = has put / have put

So:

• μπορεί να έχει βάλει
  literally something like may has put but naturally it means may have put or might have put

It is a very common Greek way to talk about a possible past action.

The base verb is βάζω = put.

Like many Greek verbs, it changes stem in different forms:

• βάζω = I put / I am putting
• έβαλα = I put (simple past)
• να βάλω = to put / that I put
• έχει βάλει = has put

So βάλει comes from the perfective stem βαλ-, not from the present stem βαζ-.

This is very normal in Greek verbs. English speakers often have to learn these stem changes as part of the verb.

Because μαξιλαροθήκη is the direct object of βάλει, and Greek normally uses the article with nouns much more often than English does.

So:

• τη μαξιλαροθήκη = the pillowcase

Also, it is in the accusative because it is the thing being put into the washing machine.

τη is a shortened form of την before a consonant.

So:

• την μαξιλαροθήκη
• τη μαξιλαροθήκη

Both represent the feminine singular accusative article, and τη is very common in normal writing and speech before consonants.

So here:

• τη μαξιλαροθήκη = the pillowcase as a direct object

Yes. Greek often builds long compound nouns.

μαξιλαροθήκη is basically:

• μαξιλάρι = pillow
• θήκη = case, holder, container

So μαξιλαροθήκη is literally something like pillow-case.
That kind of word-building is very common in Greek and often helps you guess meanings.

στο is a contraction of:

• σε + το = στο

Depending on context, σε can mean in, into, at, on, to.

With a verb like βάζω (put), English usually prefers in / into, so:

• στο πλυντήριο = in the washing machine / into the washing machine

Also, πλυντήριο here means washing machine.

The comma separates the main statement from the reason clause.

• main idea: Η μαμά μου μπορεί να έχει βάλει τη μαξιλαροθήκη στο πλυντήριο
• reason: γιατί δεν είναι πια στο κρεβάτι

Greek often uses a comma before a because clause like this, especially when the second part is clearly explaining the first.

It can mean both.

• Γιατί έφυγες; = Why did you leave?
• Έφυγα γιατί κουράστηκα. = I left because I got tired.

In this sentence, it means because, not why.
The structure and punctuation make that clear.

Here πια means anymore or no longer.

With negation, a very common pattern is:

• δεν ... πια = not ... anymore / no longer

So:

• δεν είναι πια στο κρεβάτι
  = it is no longer on the bed
  = it isn't on the bed anymore

Because Greek often leaves the subject unstated when it is obvious from context.

In English, you need:

• because it isn’t on the bed anymore

In Greek, the subject can be omitted if everyone knows what is meant.
Here, the missing thing is clearly the pillowcase, so Greek does not need to say it.

This is very common in Greek and is one of the first things English speakers notice.