Jirani yetu alijifungua mapacha mwezi uliopita.

In Swahili, possessives normally come after the noun, not before it. So jirani yetu is literally neighbor our.

This is a very common pattern:

• rafiki yangu = my friend
• mwalimu wetu = our teacher
• jirani yetu = our neighbor

This is an example of agreement working in two different places.

• yetu is the possessive form normally used with jirani
• a- is the subject marker for a singular animate person: he/she

So Swahili is treating jirani as a noun that takes yetu in the noun phrase, but since the neighbor is a person, the verb uses the normal human subject marker a-.

This kind of mixed pattern is normal with some Swahili nouns referring to people.

You can break alijifungua down like this:

• a- = he/she
• -li- = past tense
• -ji- = reflexive marker
• -fungua = verb root

So grammatically it is built from several pieces, but as a whole kujifungua means to give birth.

The -ji- is the reflexive marker, often meaning something like oneself.

But in this verb, it is best to learn kujifungua as a fixed expression meaning to give birth. Even though the verb is historically related to fungua = open, learners should usually treat kujifungua as its own vocabulary item, not translate it piece by piece every time.

By itself, a- can mean he or she. Swahili does not mark gender in the third-person singular the way English does.

In this sentence, we know it must be she only because the verb alijifungua means gave birth.

Because Swahili does not need a preposition there.

In English, we say gave birth to twins, but in Swahili the structure is simply:

Verb + object

So:

• alijifungua mapacha = gave birth to twins

That is a normal Swahili pattern.

Mapacha is plural and means twins.

The singular form is pacha, meaning one twin. In this sentence, mapacha is used because the neighbor gave birth to two babies.

Literally, mwezi uliopita means the month that passed.

That is the normal Swahili way to say last month:

• mwezi = month
• uliopita = that passed / that went by

So even though English uses a special word last, Swahili often expresses the idea as the month that passed.

Because uliopita has to agree with mwezi.

Mwezi belongs to a noun class that takes u- agreement here, so the modifier becomes uliopita. This is the same idea you see elsewhere in Swahili: words that describe or relate to a noun often change form to match that noun’s class.

So:

• mwezi uliopita = last month

It describes the whole action: the giving birth happened last month.

So the meaning is:

• Our neighbor gave birth to twins last month

It does not mean something like last month’s twins.

Swahili often puts time expressions at the end of the sentence, where they modify the whole event.

Yes. Swahili allows some flexibility with time expressions.

For example, you could also say:

Mwezi uliopita, jirani yetu alijifungua mapacha.

That still means the same thing. Putting the time phrase first just gives it a little more emphasis.

Swahili does not have articles like English a/an and the.

Whether something is definite or indefinite is usually understood from:

• context
• possessives
• demonstratives
• the situation

Here, jirani yetu already feels definite because our neighbor clearly refers to a specific person.