رأي اختي مو متل رأيي، بس بالنهاية وافقنا على نفس الشي.

A reasonable Levantine-style pronunciation is:

ra2y ekhti mu mitl ra2yi, bas bin-nihāye wāfa2na ʿa nafs ish-shi

A few notes:

• 2 represents the sound ء / hamza
• ʿ represents ع
• على is often pronounced shorter in speech, like ʿa
• الشي is pronounced ish-shi because ش is a sun letter

Exact pronunciation will vary a bit by country and speaker.

Because Arabic often leaves out the verb to be in the present tense.

So instead of saying:

• My sister’s opinion is not like mine

Levantine says something more like:

• My sister’s opinion not like mine

This is completely normal.
If you wanted past tense, you would usually use كان:

• كان رأي اختي مو متل رأيي = My sister’s opinion wasn’t like mine

مو is a very common Levantine way to say not.

So:

• مو متل رأيي = not like my opinion

Yes, it is similar to مش. Both can mean not, and which one is more common depends on the region and the speaker.

For example:

• مو كبير = not big
• مش كبير = not big

In this sentence, مو sounds natural.

This is an iḍāfa structure, also called a construct phrase.

Pattern:

• noun + noun/pronoun = X of Y

So:

• رأي اختي literally = opinion of my sister
• natural English = my sister’s opinion

Important point:

• the first noun in an iḍāfa usually does not take ال
• so رأي اختي is correct, not الرأي اختي

Also, اختي here means my sister:

• أخت = sister
• أختي / اختي = my sister

In casual writing, people often leave out the hamza and write اختي instead of أختي.

Because the noun itself already ends in a ي sound, and then you add the possessive suffix -ي meaning my.

So:

• رأي = opinion
• رأيي = my opinion

You are basically seeing:

• the ي that is part of رأي
• plus the ي suffix for my

That is why it looks doubled in writing.

Yes. متل is the common Levantine form of مثل, meaning like.

So:

• مو متل رأيي = not like my opinion

You will hear:

• متل in Levantine speech
• مثل in Standard Arabic, and sometimes in careful speech

Both are related, but متل is the one that sounds most natural here.

Here, بس means but.

So:

• ..., بس بالنهاية ... = ..., but in the end ...

Be careful: بس can also mean only in other contexts.

Examples:

• بدي قهوة بس = I only want coffee
• كنت تعبان، بس رحت = I was tired, but I went

In your sentence, it clearly means but.

بالنهاية means in the end, eventually, or after all that.

It is made of:

• بـ = in / at
• النهاية = the end

So literally:

• بالنهاية = in the end

It is a very common expression in speech.
A similar Levantine phrase is بالآخر.

وافقنا is the past tense verb meaning we agreed or we approved.

Breakdown:

• وافق = he agreed / approved
• وافقنا = we agreed

So -نا is the ending for we.

In this sentence:

• وافقنا على نفس الشي = we agreed on the same thing

A related verb you may also hear a lot is اتفقنا = we agreed.

Because وافق على is the normal pattern when you mean agree to / agree on / approve of something.

So:

• وافقنا على نفس الشي = we agreed on the same thing

The preposition على is part of how this verb commonly works.

Compare:

• وافق على الفكرة = He agreed to the idea
• وافقت على القرار = I agreed to the decision

Without على, the meaning may sound incomplete or different depending on context.

نفس الشي means the same thing.

Breakdown:

• نفس = same
• الشي = the thing

So together:

• نفس الشي = the same thing

As for شي:

• شي is the common colloquial Levantine form of Standard Arabic شيء
• in everyday speech, speakers usually say شي, not full شيء

Also, because of the ال, الشي is pronounced ish-shi in speech.

So the phrase sounds very natural in Levantine:

• وافقنا على نفس الشي = we agreed on the same thing