اختي خبت المفتاح تحت الدفتر، وبعدين نسيت وين خبته.

It is Levantine colloquial Arabic, not standard formal Arabic.

Clues include:

• وين = where in Levantine. In MSA, you would usually say أين.
• وبعدين = and then / after that, a very common spoken expression.
• Informal spelling like اختي instead of the more standard أختي.

So this is the kind of sentence you would hear in everyday conversation.

Yes—in more standard spelling, you would usually write أختي.

In casual Levantine writing, people often:

• drop hamzas
• ignore some formal spelling rules
• write more like they speak

So اختي and أختي both mean my sister here. The informal version is very common in texting and everyday writing.

خبت means she hid.

It comes from the verb خبّى = to hide something.

A useful detail: in informal Arabic writing, short vowels and the shadda are often not written. So خبت is standing for something like خبّت in pronunciation/spoken form.

Here:

• اختي خبت المفتاح = My sister hid the key

Because Arabic often leaves the subject pronoun out when the verb already shows it.

In English, you say:

• she hid

In Arabic, the verb itself already tells you the subject:

• خبت = she hid

So saying هي خبت is possible for emphasis, but normally unnecessary.

المفتاح means the key, with the definite article الـ.

Arabic uses الـ the way English uses the. So:

• مفتاح = a key / key
• المفتاح = the key

In this sentence, it is a specific key already known in the situation, so the key makes sense.

It means under the notebook.

Breakdown:

• تحت = under
• الدفتر = the notebook

So:

• خبت المفتاح تحت الدفتر = she hid the key under the notebook

وبعدين means and then, then, or after that.

It is made of:

• و = and
• بعدين = later / then / afterwards

So it links the two actions:

1. she hid the key
2. then she forgot where she hid it

It is one of the most common spoken connectors in Levantine Arabic.

وين means where in Levantine Arabic.

Comparison:

• وين = spoken Levantine where
• أين = formal / MSA where

So in everyday speech, وين is the normal choice.

Examples:

• وين البيت؟ = Where is the house?
• نسيت وين خبته = she forgot where she hid it

This is a very good question, because in informal Arabic writing, نسيت can look ambiguous without vowels.

Here, context tells us it means she forgot, because the subject of the story is my sister:

• اختي خبت... وبعدين نسيت...

In speech, the pronunciation usually helps distinguish forms, and context does the rest.

So in this sentence, the meaning is clearly:

• Then she forgot...

not

• Then I forgot...

خبته means she hid it.

It is:

• the verb خبّى = to hide
• plus the attached object pronoun ـه = it / him

Here ـه refers to المفتاح (the key), which is grammatically masculine in Arabic.

So:

• خبته = hid it
• more fully in context: where she hid it

In Arabic, it is much more natural here to keep the object pronoun and say where she hid it.

So:

• وين خبته = where she hid it

The it refers back to the key.

English sometimes leaves the object unspoken in some contexts, but Arabic usually prefers to state it with the attached pronoun if the meaning is hide it rather than just hide in general.

Arabic does not need an extra word like English sometimes does in structures such as where she hid it.

The sequence is simply:

• وين = where
• خبته = she hid it

So the whole phrase works directly as:

• وين خبته = where she hid it

This is very normal Arabic sentence structure.

A rough pronunciation would be:

ikhti khabbat il-miftaa7 ta7t id-daftar, w ba3dein nisyit wein khabbat-o

Notes:

• 7 represents the Arabic letter ح
• 3 represents the Arabic letter ع
• pronunciation varies by country and city, so this is only an approximation

The important rhythm is:

• ikhti khabbat il-miftaa7
• ta7t id-daftar
• w ba3dein nisyit wein khabbat-o

It is basically:

1. اختي خبت المفتاح تحت الدفتر

   • My sister hid the key under the notebook

2. وبعدين نسيت وين خبته

   • and then she forgot where she hid it

So the pattern is:

• subject + verb + object + place
• then
• connector + verb + embedded question clause

This kind of structure is extremely common in everyday spoken Arabic.