باب المطبخ متسخ اليوم، لكن باب الغرفة نظيف.

In Modern Standard Arabic, the present tense of to be is usually not expressed in simple sentences like this.

So:

باب المطبخ متسخ
literally looks like
the kitchen door dirty

but it means
The kitchen door is dirty.

This is called a nominal sentence. If you wanted was or will be, then Arabic would normally use a verb such as كان or سيكون.

It is an iḍāfa construction, often translated as the kitchen door or literally door of the kitchen.

The pattern is:

• باب = door
• المطبخ = the kitchen

Together, they form one unit:

باب المطبخ = the kitchen door

This structure is extremely common in Arabic and often corresponds to English noun + noun phrases like:

• book cover
• school door
• room key

Because in an iḍāfa construction, the first noun normally does not take ال.

So the correct form is:

• باب المطبخ = the kitchen door

not:

• الباب المطبخ ❌

The definiteness of the whole phrase comes from the second noun:

• بابُ مطبخٍ = a kitchen door
• بابُ المطبخِ = the kitchen door

So even without ال on باب, the whole phrase can still be definite.

Because متسخ and نظيف are predicate adjectives, not adjectives directly attached to the noun inside a noun phrase.

Compare these two ideas:

• بابُ المطبخِ متسخٌ = The kitchen door is dirty.
• بابُ المطبخِ المتسخُ = the dirty kitchen door

In the first sentence, متسخ is the predicate, so it is normally indefinite.
In the second, المتسخ is an adjective modifying the noun directly, so it must match the noun phrase in definiteness.

That is a very common Arabic pattern:

• البيت كبير = The house is big
• البيت الكبير = the big house

Because the adjective agrees with باب, not with الغرفة.

In باب الغرفة, the main noun is باب = door, and باب is masculine.
So the adjective must also be masculine:

• باب الغرفة نظيف

Even though الغرفة is feminine, it is only the second noun in the iḍāfa phrase.

A good comparison:

• نافذة الغرفة نظيفة = The room’s window is clean

Here نافذة is feminine, so the adjective becomes نظيفة.

Because the sentence is contrasting two doors, not a door and a room.

• باب المطبخ متسخ اليوم = The kitchen door is dirty today
• لكن باب الغرفة نظيف = but the room door is clean

If you said:

• لكن الغرفة نظيفة

that would mean:

• but the room is clean

So repeating باب is necessary to keep the meaning clear.

Here لكن means but and introduces a contrast between the two clauses.

So:

• باب المطبخ متسخ اليوم، لكن باب الغرفة نظيف
• The kitchen door is dirty today, but the room door is clean

Yes, لكن and ولكن can both mean but in MSA.
ولكن is just a longer form and is also very common.

Because اليوم is simply the standard Arabic word for today.

Historically and literally, it is related to the day, but in normal usage اليوم functions as the adverb today.

So in this sentence:

• متسخ اليوم = dirty today

The ال here is just part of the normal word form learners need to memorize.

Yes. Arabic allows some flexibility with adverbials like اليوم.

The given sentence:

• باب المطبخ متسخ اليوم

is very natural.

But you could also say:

• اليوم باب المطبخ متسخ

which gives more emphasis to today.

The meaning stays basically the same, but the focus can shift slightly depending on placement.

A fully vocalized version would be:

بَابُ الْمَطْبَخِ مُتَّسِخٌ الْيَوْمَ، لَكِنْ بَابُ الْغُرْفَةِ نَظِيفٌ.

This shows the grammatical roles more clearly:

• بَابُ — nominative, because it is the subject/topic of the nominal sentence
• الْمَطْبَخِ — genitive, because it is the second noun in the iḍāfa
• مُتَّسِخٌ — nominative predicate
• الْيَوْمَ — adverbial accusative
• بَابُ الْغُرْفَةِ نَظِيفٌ — same pattern again

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

Not exactly.

A very literal breakdown would be:

• باب المطبخ = door of the kitchen
• متسخ = dirty
• اليوم = today
• لكن = but
• باب الغرفة = door of the room
• نظيف = clean

So the structure is closer to:

The kitchen door dirty today, but the room door clean.

Arabic and English organize noun phrases and is/are differently, so it is better to learn the Arabic pattern as its own structure rather than trying to match every word directly.