هذه الشقة مفروشة.

A careful MSA pronunciation is:

hādhihi ash-shaqqatu mafrūshah

In normal pausal pronunciation (how you often hear it at the end of a sentence), it is often said more like:

hādhihi ash-shaqqa mafrūsha

A few pronunciation notes:

• هذه = hādhihi
• الشقة begins with ش, like sh
• The ال in الشقة becomes ash- because ش is a sun letter
• ق in شقة is a deep q sound, not an English k
• مفروشة = mafrūshah, with sh in the middle

Because الشقة is a feminine noun.

In Arabic, this changes according to gender:

• هذا = this for masculine nouns
• هذه = this for feminine nouns

Since شقة (apartment) is feminine, the correct phrase is:

هذه الشقة = this apartment

A major clue is the ة at the end, called tāʾ marbūṭa.

Very often, nouns ending in ة are feminine. So:

• شقة = feminine
• therefore it takes feminine agreement:
  • هذه
  • مفروشة

This is a very common pattern in Arabic.

Because the adjective must agree with the noun in gender.

Since الشقة is feminine, the adjective is also feminine:

• masculine: مفروش
• feminine: مفروشة

So:

• بيت مفروش = a furnished house
• شقة مفروشة = a furnished apartment

This kind of adjective agreement is basic and very important in Arabic.

In Arabic, in the present tense, the verb to be is usually not expressed in simple statements.

So Arabic says literally:

هذه الشقة مفروشة = this apartment furnished

But in natural English, that means:

This apartment is furnished.

This is completely normal in Arabic.

It is functioning as an adjective here, but historically and grammatically it is related to a passive participle.

It comes from the verb فرش meaning to furnish / spread / carpet.

So:

• مفروش = furnished (masculine)
• مفروشة = furnished (feminine)

In this sentence, it describes the apartment, so for a learner it is easiest to think of it as an adjective: furnished.

In Arabic, demonstratives like هذا and هذه are commonly followed by a noun with ال.

So Arabic naturally says:

• هذه الشقة
• literally: this the-apartment
• meaning: this apartment

This is the normal Arabic structure, even though it looks strange from an English point of view.

Because ش is a sun letter.

When ال comes before a sun letter, the l sound is not pronounced. Instead, the following consonant is doubled.

So:

• written: الشقة
• pronounced: ash-shaqqa

This happens with many letters, such as ت، د، ر، س، ش، ص، ض، ط، ظ، ل، ن.

In fully vocalized formal Arabic, the sentence would be:

هٰذِهِ الشَّقَّةُ مَفْرُوشَةٌ

The endings are:

• الشقةُ with -u because it is the subject
• مفروشةٌ with -un because it is the predicate adjective

However, in normal speech and in most everyday writing, these case endings are usually not pronounced.

So learners will often hear:

هذه الشقة مفروشة

without the final short vowels.

Yes.

شقة can be translated as:

• apartment
• flat

Which English word is better depends on the variety of English:

• American English usually prefers apartment
• British English often prefers flat

So the Arabic sentence can match either one.

A common MSA negative version is:

هذه الشقة ليست مفروشة = This apartment is not furnished

Here:

• ليست is the feminine form used with a feminine subject
• مفروشة stays feminine because it still describes الشقة

So the structure remains very similar.

In MSA, the most standard form is:

هذه الشقة مفروشة

Putting the demonstrative after the noun, as in الشقة هذه, is more typical of spoken dialects than careful Modern Standard Arabic.

So for MSA, learners should prefer:

هذه الشقة مفروشة

The pattern is:

demonstrative + noun + adjective/predicate

More specifically:

• هذه = demonstrative, this
• الشقة = noun, the apartment
• مفروشة = predicate adjective, furnished

So the sentence is a type of nominal sentence in Arabic: it begins with a noun phrase, not a verb.

That is a very common Arabic sentence type.