في العشاء نأكل الارز مع السمك، وبعد العشاء أشرب ماء.

Arabic word order is more flexible than English word order. Starting with في العشاء puts the time first, like saying At dinner, ... or As for dinner, ....

So:

في العشاء نأكل الأرز مع السمك
means literally something like At dinner, we eat rice with fish.

This is a very normal way to organize a sentence in Arabic, especially when the speaker wants to set the scene first.

في often means in, but with time expressions it can also mean at or during.

So here:

• في العشاء = at dinner / during dinner
• not a literal physical inside

This is similar to how في works in expressions like:

• في الصباح = in the morning
• في الليل = at night

Arabic and English do not use definiteness in exactly the same way.

In Arabic, generic or familiar things often appear with الـ even when English uses no the. So:

• الأرز can simply mean rice
• السمك can simply mean fish

In this sentence, the speaker is talking about a usual dinner meal, so the definite article sounds natural in Arabic.

In careful Modern Standard Arabic, the standard spelling is الأرز.

Writing الارز without the hamza is common in informal writing, but it is less standard. So for MSA, learners should usually write:

الأرز

You may also sometimes see الرز in many real-world texts and speech, but الأرز is the safest standard form to learn.

Because س is a sun letter.

When الـ comes before a sun letter, the l sound is not pronounced; it assimilates to the next consonant. So:

• السمك is written with الـ
• but pronounced as-samak

By contrast, العشاء begins with ع, which is a moon letter, so the l is pronounced there.

Because the sentence changes subject.

• نأكل = we eat
• أشرب = I drink

So the speaker is saying:

• At dinner, we eat rice with fish
• and after dinner, I drink water

This kind of subject shift is completely possible in Arabic, just as in English.

Arabic verbs usually already show the subject, so separate subject pronouns are often unnecessary.

For example:

• نأكل already means we eat
• أشرب already means I drink

So Arabic often leaves out نحن and أنا unless the speaker wants emphasis, contrast, or extra clarity.

If you added them, it would be:

• نحن نأكل
• أنا أشرب

But in normal sentences, that is often not needed.

Here ماء is indefinite because it means water in a general sense.

So:

• أشرب ماء = I drink water

If you said أشرب الماء, it would sound more like I drink the water, meaning some specific water already known from context.

Arabic often uses the indefinite form for substances in a general meaning, just as English does.

If you wrote the sentence with full case endings, it would look like this:

في العشاءِ نأكل الأرزَ مع السمكِ، وبعدَ العشاءِ أشرب ماءً.

The reasons are:

• العشاءِ after في is genitive
• الأرزَ is the direct object of نأكل, so it is accusative
• السمكِ after مع is genitive
• بعدَ is commonly accusative in this kind of adverbial use
• العشاءِ after بعد is genitive
• ماءً is the direct object of أشرب, so it is accusative

In normal everyday Arabic writing, these short vowels are usually omitted.

Because و is a clitic in Arabic, meaning it is written attached to the following word.

So:

• و = and
• بعد = after
• وبعد = and after

This is completely normal. Arabic also attaches other short particles and prepositions in similar ways.

Not necessarily. In Arabic, the imperfect form can describe:

• the present
• repeated actions
• habits
• general truths

In this sentence, the most natural reading is a habitual one:

At dinner we eat rice with fish, and after dinner I drink water.

So it sounds like a routine or usual practice, not just something happening right this second.