في المساء أفتح الثلاجة وآخذ ماء.

Because the verbs already show the subject.

• أفتح = I open
• آخذ = I take / get

In Arabic, subject pronouns are often omitted when the verb makes the subject clear. So:

• أفتح الثلاجة = I open the fridge
• أنا أفتح الثلاجة = also possible, but more emphatic, like I open the fridge

So leaving out أنا is completely normal.

They are in the imperfect form, which usually covers:

• the present
• the habitual present
• sometimes the future, depending on context

In this sentence, the meaning is most naturally habitual or simple present:

• في المساء أفتح الثلاجة وآخذ ماء = In the evening, I open the fridge and get water

So Arabic uses the same basic verb form here where English might use I open or I usually open.

Arabic often puts time expressions at the beginning of the sentence. That is very natural.

So:

• في المساء أفتح الثلاجة وآخذ ماء
• literally: In the evening, I open the fridge and get water

You could also put the time expression later, but starting with it is common when you want to set the scene first.

في means in, and المساء means the evening.

So في المساء is the normal way to say in the evening.

Also, Arabic often uses the definite article in time expressions like this. So المساء here is exactly what you would expect in standard Arabic.

This is because of the sun letter / moon letter rule.

• المساء starts with م, which is a moon letter, so the ل in الـ is pronounced:
  • al-masāʾ
• الثلاجة starts with ث, which is a sun letter, so the ل is not pronounced separately; it assimilates to the next consonant:
  • written: الثلاجة
  • pronounced: ath-thallāja

So the spelling stays the same, but the pronunciation changes depending on the first letter of the noun.

Because in Arabic, the conjunction و meaning and is written as a prefix attached to the following word.

So:

• و + آخذ → وآخذ

This is completely normal Arabic spelling. The same happens with many short particles, such as:

• و = and
• ب = with / by
• ل = for / to
• ف = so / then

This is a spelling issue caused by two hamzas coming together.

The verb comes from أخذ. In the first-person imperfect, the form would historically give something like أأخذ. In standard spelling, this is written as آخذ with آ.

So:

• آخذ = I take

This is the normal spelling you should learn.

Because here ماء is being used as an indefinite mass noun, meaning something like:

• water
• some water

Arabic often leaves mass nouns indefinite in this kind of sentence.

So:

• آخذ ماء = I get water / some water
• آخذ الماء = I get the water

Using الماء would usually mean a specific, known water, not just water in general.

In fully vocalized formal Arabic, yes.

Since ماء is the direct object of آخذ, it would normally be written:

• ماءً

And the full sentence with case endings could be written as:

• فِي المَساءِ أَفتَحُ الثَّلّاجَةَ وَآخُذُ ماءً

But in normal everyday Arabic writing, short vowels and case endings are usually omitted, so ماء without the ending is very common in writing.

Yes. In fully vocalized MSA, several words would show case or mood endings:

• فِي المَساءِ — المساءِ is genitive because it comes after في
• أَفتَحُ — the verb ends in -u in the indicative
• الثَّلّاجَةَ — accusative as the direct object of أفتح
• وَآخُذُ — indicative -u
• ماءً — accusative as the direct object of آخذ

But in ordinary writing, these endings are usually not written.

Yes, it is grammatical and understandable.

But depending on context, native-style wording could vary:

• آخذ ماءً = I get/take water
• أشرب ماءً = I drink water
• آخذ زجاجةَ ماءٍ = I take a bottle of water
• آخذ بعضَ الماءِ = I take some water

So آخذ ماء is fine, but if you want to sound more precise, Arabic often adds a word like some, a bottle of, or simply uses drink if that is the real action.

ماء is pronounced approximately māʾ.

Important points:

• ما gives a long ā
• the final ء is a hamza, a glottal stop

So it is not just maa with a long vowel flowing off at the end. There is a small stop at the end:

• māʾ

That final hamza is an important part of the word.

Both can work, depending on how natural the English translation is.

• آخذ literally often means take
• but in many everyday contexts, English would more naturally say get

So in this sentence:

• literal sense: I take water
• natural English sense: I get some water

That does not mean the Arabic is strange; it just means English and Arabic package everyday actions a little differently.