اختي بتخاف من الكلب اللي عند جيراننا.

It is Egyptian Arabic.

A few clear clues are:

• بتخاف: the بـ prefix is a common Egyptian present-tense marker.
• اللي: this is the everyday Egyptian relative word for that / which / who.
• اختي without the hamza is also very common in informal writing.

A more MSA-style version would be:

أختي تخاف من الكلب الذي عند جيراننا

A common Egyptian-style pronunciation is:

okhti bitkhaf men il-kalb illi ʿand giranna

A few notes:

• ج in Egyptian is usually a hard g sound.
• خ sounds like kh in Scottish loch.
• ع is the sound often written ʿ.
• You may also see transliterations like el-kalb or elli. That is normal.

In careful spelling, it is usually written أختي.

In informal writing, especially in texts, chats, and social media, people often leave out the hamza, so اختي is very common. It is the same word and means the same thing.

They are attached possessive pronouns:

• -ي = my
• -نا = our

So:

• اختي / أختي = my sister
• جيراننا = our neighbors

بتخاف means she is afraid or she fears.

It comes from the verb خاف = to fear / to be afraid.

In Egyptian Arabic, the بـ prefix usually marks the normal present tense. So بتخاف can express:

• a general fact
• a habit
• a present situation

Also, Arabic does not need a separate word for English is here. The verb بتخاف already carries the present meaning.

Because the subject اختي tells you.

By itself, بتخاف can be ambiguous in Egyptian Arabic. It can mean:

• she is afraid
• you (masculine singular) are afraid

But once you add اختي, the meaning is clearly my sister is afraid.

Because خاف normally goes with من in Arabic.

So the pattern is:

خاف من = to be afraid of

Literally, Arabic is closer to be afraid from, but in natural English we say afraid of. This is just a verb-preposition combination you need to learn as a unit.

الكلب means the dog.

It is definite because the sentence is talking about a specific dog, not just any dog. The next part, اللي عند جيراننا, identifies which dog:

the dog that is at our neighbors' place

If it were كلب without الـ, it would mean a dog.

اللي is the Egyptian Arabic relative word meaning:

• that
• which
• who

One very useful thing about اللي is that it does not change for gender or number in everyday Egyptian.

Here:

الكلب اللي عند جيراننا

means:

the dog that is at our neighbors' place
or
the dog that our neighbors have

عند often means at, with, or in the possession of, depending on context.

Here, عند جيراننا means something like:

• at our neighbors' place
• with our neighbors
• in our neighbors' possession

So the sentence refers to a dog associated with the neighbors.

Yes.

• جار = neighbor
• جيران = neighbors

This is a broken plural, which means the word changes form internally instead of just taking a simple plural ending.

Then -نا is added:

جيراننا = our neighbors

Because in Egyptian Arabic, subject + verb order is very common in everyday speech.

So:

اختي بتخاف...

sounds natural and conversational.

Arabic can also use other word orders depending on style and emphasis, but this noun-first pattern is extremely common in spoken Egyptian.

Yes, that is a very natural English interpretation.

Literally, the Arabic says:

my sister is afraid of the dog that is at our neighbors' place

In real usage, that often amounts to:

My sister is afraid of our neighbors' dog.

Both are good ways to understand it, depending on context.