نحن نعيش في هذا المبنى منذ شهرين، وما زلت لا أعرف كل الجيران.

نحن is not strictly necessary.

Arabic verbs already show the subject, so نعيش by itself already means we live.
The speaker includes نحن for clarity, emphasis, or simply natural style.

So both are possible:

• نحن نعيش في هذا المبنى...
• نعيش في هذا المبنى...

The first is a little more explicit.

Because the action/state started in the past and is still continuing now.

In Arabic, the present tense is commonly used for something that began earlier and continues into the present, especially with منذ.

So:

• نعيش منذ شهرين = we have been living for two months / we have lived for two months

This is very natural in Arabic, even though English often uses a present perfect or present perfect progressive form.

Here منذ means for, because it is followed by a period of time:

• منذ شهرين = for two months

But منذ can also mean since when it is followed by a starting point in time:

• منذ يومين = for two days
• منذ يوم الجمعة = since Friday
• منذ عام 2020 = since 2020

So the exact English translation depends on what comes after it.

Because شهرين is the dual form in the genitive/accusative case, and it comes after منذ.

The singular is:

• شهر = month

The dual is:

• شهران in the nominative
• شهرين in the accusative/genitive

Since منذ is treated like a preposition here, the noun after it appears in the genitive form, so:

• منذ شهرين

This is the normal way to say for two months.

Because the subject really changes.

• نحن نعيش = we live
• ما زلت لا أعرف = I still do not know

The speaker is saying:

• We live in this building
• but I still do not know all the neighbors

So the first clause refers to the speaker and at least one other person, while the second clause refers only to the speaker.

That is why the verb changes from first person plural to first person singular.

ما زلت means I still am / I still continue to.

It comes from the verb زال in an expression that is used to talk about something continuing. In modern usage, ما زال and its forms are a very common way to say still.

So:

• ما زلت لا أعرف = I still do not know

Other forms are:

• ما زال = he still...
• ما زالت = she still...
• ما زلنا = we still...
• ما زالوا = they still...

This is a very common question.

In ما زلت لا أعرف, the ما is part of the fixed expression ما زال meaning still or continue to. Then لا negates the following verb أعرف.

So the whole phrase means:

• I still do not know

It is best to learn ما زال as one unit here, rather than trying to interpret each negative word separately.

Yes. لا أزال is also a standard and very common way to say I still...

So both are correct:

• وما زلت لا أعرف كل الجيران
• ولا أزال لا أعرف كل الجيران

They are very close in meaning.
For learners, both are useful, but ما زلت is especially common in everyday usage and in writing.

Because كل الجيران means all the neighbors, referring to a specific known group.

• كل الجيران = all the neighbors
• كل جيران... can appear in other structures, often when the noun after it is linked to something else, such as all the neighbors of the building

In your sentence, the speaker means the complete set of neighbors in this building, so the definite form الجيران is natural.

The singular is جار = neighbor.

The plural جيران is a broken plural, so it does not use a simple ending like -ون or -ات.

• جار = neighbor
• جيران = neighbors

This is a very common noun, so it is worth memorizing as a pair.

Yes, often you can.

• نحن نعيش في هذا المبنى = we live in this building
• نحن نسكن في هذا المبنى = we live/reside in this building

In this context, نسكن may sound a little more directly connected to residence, while نعيش is also perfectly natural. In many everyday situations, both work.

A learner should know both verbs:

• عاش / يعيش = to live
• سكن / يسكن = to reside, dwell

It is pronounced al-mabnā, with a final long ā sound.

The final ى is called alif maqṣūrah. Even though it looks different from ordinary ا, it is pronounced as a long ā.

So:

• المبنى = al-mabnā = the building

This spelling is normal for some Arabic nouns and verbs, and you simply learn it as part of the word.