بعد العشاء أضع الطبق والملعقة في المطبخ، ثم أغلق الثلاجة.

Because Arabic often puts a time expression at the beginning of the sentence to set the scene. بعد العشاء tells you when the actions happen, and then the main actions follow: أضع ... ثم أغلق ...

This is very natural in MSA. English can do the same with phrases like After dinner, I put...

بعد here means after, but grammatically it acts like a time noun/adverb in an iḍāfa construction.

In a fully vowelled form, it would be:

بَعْدَ العَشَاءِ

• بعدَ = a time expression, usually with fatḥa
• العشاءِ = the noun after it, in the genitive because it is the second part of the iḍāfa

So literally, it is something like after of the dinner, though of course that is not how you translate it in English.

In MSA, meal names are often used with الـ when talking about them in a general, familiar way, like breakfast, lunch, or dinner as known daily meals.

So العشاء is very natural for dinner / the evening meal.

Also, after بعد, using بعد العشاء is a very common fixed expression for after dinner.

Because the verb itself already tells you the subject.

• أضع = I put
• أغلق = I close

The prefix أ on these present-tense verbs marks first person singular.

You could add أنا if you want emphasis:

بعد العشاء أنا أضع...

But in normal Arabic, that is usually unnecessary.

In Arabic, the present tense (المضارع) is used not only for actions happening right now, but also for habitual or regular actions.

So أضع and أغلق can mean:

• I am putting / I am closing
• I put / I close as a habit or routine

In this sentence, the intended meaning is a habitual sequence, so the present tense is exactly what you would expect.

They do different jobs:

• و means and and simply joins words or phrases.
  • الطبق والملعقة = the plate and the spoon
• ثم means then and shows sequence, often with a sense that one action comes after the other.
  • ثم أغلق الثلاجة = then I close the refrigerator

So و just connects items, while ثم connects actions in order.

Because the sentence is talking about one plate and one spoon.

Arabic uses the singular when the meaning is singular, just like English does. If the meaning were plural, you would use plural nouns, for example:

• الأطباق = plates
• الملاعق = spoons

So the singular here is simply matching the meaning.

في means in / inside, so it focuses on the location where the objects end up.

• أضع ... في المطبخ = I put ... in the kitchen

If you used إلى, that would emphasize movement to / toward the kitchen:

• إلى المطبخ = to the kitchen

With put, Arabic often uses في when the important idea is the final placed location.

Because ordinary Arabic writing usually does not show the short vowel case endings.

In a fully vowelled version, you would see something like:

بَعْدَ العَشَاءِ أَضَعُ الطَّبَقَ وَالمِلْعَقَةَ فِي المَطْبَخِ، ثُمَّ أُغْلِقُ الثَّلَّاجَةَ.

Here the endings show the grammar:

• الطبقَ = direct object, so accusative
• الملعقةَ = direct object, so accusative
• المطبخِ = after في, so genitive
• الثلاجةَ = direct object, so accusative

In normal unvowelled text, these final short vowels are omitted, so the words look unchanged.

Because they come right after the verb and are joined by و, so they form a coordinated object phrase:

• أضع الطبق = I put the plate
• أضع الملعقة = I put the spoon
• together: أضع الطبق والملعقة

So both nouns are things being put. This is why both are understood as direct objects of أضع.

Yes. In الثلاجة, the الـ is followed by ث, which is a sun letter, so the l sound of الـ is assimilated.

So الثلاجة is pronounced approximately:

ath-thallāja

not al-thallāja

A few useful pronunciation notes:

• ث sounds like th in think
• the ل in the word itself is doubled
• in MSA, ج is usually pronounced like j in judge

Also, compare this with العشاء: there the ل of الـ is pronounced normally, because ع is not a sun letter.

In this sentence, أغلق is the present-tense first-person singular form in ordinary unvowelled writing.

Fully vowelled, it is:

أُغْلِقُ = I close

The dictionary form you usually learn is the past tense third person masculine singular:

أَغْلَقَ = he closed

So the written form أغلق can represent different vocalizations depending on context. In this sentence, because the sentence is about I, it is understood as أُغْلِقُ.

A fully vowelled version is:

بَعْدَ العَشَاءِ أَضَعُ الطَّبَقَ وَالمِلْعَقَةَ فِي المَطْبَخِ، ثُمَّ أُغْلِقُ الثَّلَّاجَةَ.

This helps show several things clearly:

• أَضَعُ = I put
• الطَّبَقَ and المِلْعَقَةَ = accusative objects
• فِي المَطْبَخِ = genitive after في
• ثُمَّ = then
• أُغْلِقُ = I close
• الثَّلَّاجَةَ = accusative object

For learners, seeing the vowelled form can make the grammar much easier to understand.