صديقتنا تنتظر ضيفة اليوم، ولذلك تريد أن ترتب البيت مبكرا.

Because the subject is صديقتنا = our female friend, which is feminine singular.

In Modern Standard Arabic, verbs agree with their subject in gender. So with a feminine singular subject, you get feminine singular verbs:

• تنتظر = she waits / she is waiting
• تريد = she wants

If the subject were masculine, you would have:

• صديقنا ينتظر...
• ...ولذلك يريد...

So the تـ at the beginning here marks she in these present-tense verbs.

صديقتنا means our female friend.

It breaks down like this:

• صديقة = female friend
• نا = our

When a word ending in ة (taa marbuuTa) is followed by a suffix like نا, the ة is pronounced and written as ت in the connected form:

• صديقة → صديقتنا

This is very common:

• سيارة = car
• سيارتنا = our car

So the ت is not a different word; it is the same feminine ending showing up before the possessive suffix.

Yes. ضيفة is the feminine form and means a female guest.

Compare:

• ضيف = a male guest
• ضيفة = a female guest

So this sentence tells you the expected guest is female. If the guest were male, the sentence would use ضيف instead.

Because Arabic verbs usually already contain the subject information.

For example:

• تنتظر already means she waits / she is waiting
• تريد already means she wants
• ترتب already means she arranges / tidies

Arabic often does not need a separate pronoun like هي unless you want emphasis or contrast.

So:

• صديقتنا تنتظر ضيفة = Our friend is waiting for a female guest

The noun صديقتنا is the explicit subject, and the verb form matches it.

Because after verbs like يريد (to want), Arabic normally uses أن before the following verb.

So:

• تريد أن ترتب البيت = she wants to tidy the house

Here:

• تريد = she wants
• أن = to
• ترتب = tidy/arrange

This is a very common pattern in MSA:

• أريد أن أذهب = I want to go
• نريد أن ندرس = we want to study
• تريد أن ترتب = she wants to tidy

With full vowel endings, ترتب after أن would be pronounced تُرَتِّبَ, because أن puts the following present verb into the subjunctive.

ولذلك means and therefore, so, or for that reason.

It is made of:

• و = and
• لذلك = therefore / for that reason

And لذلك itself comes from:

• لِـ = for
• ذلك = that

So literally it is something like and for that or and for that reason.

In this sentence, it connects the two ideas:

• she is waiting for a guest today
• therefore, she wants to tidy the house early

In Arabic, البيت literally means the house, but very often this is the natural way to refer to the home/house in context.

So here ترتب البيت is best understood as:

• tidy the house
• or more naturally in English, tidy the house/home

Arabic does not always need a possessive like her house if the context already makes it obvious whose house is meant.

If you wanted to say her house explicitly, you could say:

• بيتها

But البيت is completely natural here.

مبكرا means early, and here it functions adverbially: it tells you when she wants to tidy the house.

So:

• أن ترتب البيت مبكرا = to tidy the house early

It is not definite because it is not the early one or an adjective attached to a noun. It is being used more like an adverb.

In fully vowelled Arabic, it would be:

• مبكرًا

This final -an ending is common when an adjective is used adverbially in MSA.

It goes with the action تنتظر.

So the meaning is:

• Our female friend is waiting today for a female guest

not:

• a today guest

In Arabic, time expressions like اليوم often come after the object or in other flexible positions. Word order is more flexible than in English.

For example, these are all possible with similar meaning:

• صديقتنا تنتظر ضيفة اليوم
• صديقتنا اليوم تنتظر ضيفة
• اليوم صديقتنا تنتظر ضيفة

The original sentence is perfectly natural.

In normal everyday Arabic writing, short vowel case endings are usually not written.

So although you see:

• ضيفة

in full formal vowelled Arabic it would be:

• ضيفةً

because it is the direct object of تنتظر.

The same applies elsewhere in the sentence:

• مبكرا would fully be مبكرًا
• ترتب after أن would fully be ترتبَ

So the grammar is there, but standard unvowelled writing usually leaves those endings off.

It can mean either, depending on context, but in this sentence the natural meaning is is waiting for.

So:

• تنتظر ضيفة = she is waiting for a female guest

Arabic انتظر often takes its object directly, without a separate word for for.

Compare the English pattern:

• wait for a guest

But in Arabic:

• ينتظر ضيفًا
• literally: he waits a guest
• naturally: he is waiting for a guest

Yes. ترتب comes from the root ر ت ب, which has to do with order and arrangement.

Related words include:

• رَتَّبَ = to arrange, put in order, tidy
• تَرْتيب = arrangement, ordering

So:

• أن ترتب البيت = to arrange / tidy the house

This is a very useful verb for everyday contexts like cleaning, organizing, and putting things in order.

A fully vowelled version would be:

صَديقتُنا تَنتَظِرُ ضَيفَةً اليَومَ، وَلِذٰلِكَ تُريدُ أَن تُرَتِّبَ البَيتَ مُبَكِّرًا.

This shows several grammatical details that are usually omitted in normal writing:

• صديقتُنا: subject ending
• تنتظرُ: indicative present
• ضيفةً: accusative direct object
• اليومَ: accusative adverbial time expression
• تريدُ: indicative present
• أن ترتبَ: subjunctive after أن
• البيتَ: accusative direct object
• مبكرًا: adverbial accusative

You do not need these vowels in ordinary reading, but they help show the grammar clearly.