النزيل في الردهة.

In Arabic, the present-tense verb to be is usually omitted.

So النزيل في الردهة is a complete sentence in MSA. It is a nominal sentence:

• النزيل = the subject/topic
• في الردهة = the predicate, literally in the lobby

If you wanted a past meaning, Arabic would normally use a verb such as كان.

في is the preposition in.

It introduces a prepositional phrase:

• في الردهة = in the lobby

A useful grammar point: after a preposition like في, the following noun takes the genitive case in fully vocalized MSA.

A fully vocalized version is:

النزيلُ في الرُّدهةِ

Why those endings?

• النزيلُ is nominative because it is the subject/topic of the nominal sentence.
• الرُّدهةِ is genitive because it comes after the preposition في.

In normal Arabic writing, these short vowels are usually omitted, so learners often see only النزيل في الردهة.

الـ is the definite article, equivalent to the.

In this sentence it appears in both nouns:

• النزيل = the guest / the occupant
• الردهة = the lobby

But in pronunciation, the ل of الـ is not clearly pronounced before some letters. This is because ن and ر are both sun letters.

So:

• النزيل is pronounced with a doubled n
• الردهة is pronounced with a doubled r

The spelling stays the same, but the pronunciation changes.

The final ة is called taa marbuuTa.

A simple rule:

• when stopping at the end of the sentence, it is usually pronounced like -ah
• in careful grammatical reading, when case endings are pronounced, it can sound like -t before the ending

So in everyday pausing pronunciation, learners often hear something like ...في الردهة with an -ah sound at the end.

Yes. النزيل is masculine singular.

Related forms include:

• النزيلة = the female guest / female occupant
• النزلاء = the guests / occupants

So you could also say:

• النزيلة في الردهة = the female guest is in the lobby
• النزلاء في الردهة = the guests are in the lobby

Yes, Arabic can do that.

The neutral, straightforward order is:

النزيل في الردهة

But you can also front the prepositional phrase for emphasis or style:

في الردهة النزيل

This can sound more marked, as if you are highlighting the location. For a beginner, the original order is the safest and most natural to produce first.

Removing الـ makes the noun indefinite.

For example:

• نزيلٌ في الردهةِ = a guest is in the lobby
• النزيلُ في ردهةٍ = the guest is in a lobby
• نزيلٌ في ردهةٍ = a guest is in a lobby

So الـ is doing the same basic job as the in English.