Akiwa anatoka famasi, baba alinunua dawa ya meno kwa sababu ile ya nyumbani ilikuwa imeisha.

Swahili often uses one verb form to set the time or situation, and another to describe the main action happening in that situation.

• akiwa comes from kuwa = to be
• in this form, it means something like while he was, as he was, or when he was
• anatoka means he is leaving or he is coming from

So Akiwa anatoka famasi means as he was leaving the pharmacy or while he was coming from the pharmacy.

Because in Swahili, the -na- tense marker does not only mean present time in the English sense. It also often shows an action that is in progress relative to another point in time.

So here:

• alinunua = he bought
• akiwa anatoka = while he was leaving / coming from

Even though anatoka looks like he is leaving, in this context it is understood as he was leaving because the main event is in the past.

It can mean either, depending on context.

kutoka basically has the idea of going out from or coming from a place. So:

• anatoka famasi can mean he is leaving the pharmacy
• it can also mean he is coming from the pharmacy

English chooses one wording or the other depending on what sounds most natural in context.

famasi means pharmacy, chemist, or drugstore.

It is a loanword. You may also see:

• farmasi as a spelling variant
• duka la dawa = medicine shop / pharmacy

All of these are understandable. In everyday speech, loanwords like famasi are very common.

alinunua breaks down like this:

• a- = he / she
• -li- = past tense
• nunua = buy

So alinunua means he bought.

This is a very useful pattern in Swahili:

• alisoma = he read / studied
• alikwenda = he went
• alikula = he ate

Because Swahili generally does not use articles like English a, an, and the.

So:

• baba can mean father, the father, or dad, depending on context
• dawa ya meno can mean toothpaste, some toothpaste, or the toothpaste, depending on context

Swahili usually lets context show whether something is definite or indefinite.

Yes, literally it is something like medicine of the teeth.

Here:

• dawa = medicine, remedy, treatment
• meno = teeth
• ya links the two nouns and agrees with dawa

In real usage, dawa ya meno can refer to toothpaste or dental medicine, depending on context. In this sentence, it most naturally means toothpaste.

You may also hear pasta ya meno for toothpaste.

kwa sababu means because.

It is followed here by a full clause:

• kwa sababu ile ya nyumbani ilikuwa imeisha
• because the one at home had run out

When you want to say because of plus a noun, you usually use kwa sababu ya.

Compare:

• kwa sababu alikuwa mgonjwa = because he was sick
• kwa sababu ya ugonjwa = because of illness

So in your sentence, kwa sababu is correct because a whole clause comes after it.

ile ya nyumbani means the one at home.

Here:

• ile = that one
• ya nyumbani = of home / at home

Swahili often leaves out a noun if it is already clear from context. So instead of repeating dawa, the sentence just says ile.

The full idea is:

• ile dawa ya nyumbani
• but Swahili shortens it to ile ya nyumbani

This is very common.

These are demonstratives, and they show different kinds of distance or remoteness.

Very roughly:

• hii = this
• hiyo = that
• ile = that one over there / that one not here

In this sentence, the toothpaste being referred to is the one at home, not the one being bought right now, so ile sounds natural.

Also, ile agrees with dawa, which is in noun class 9 singular.

nyumbani means at home, home, or in the house.

So ya nyumbani here means the one at home.

It does not necessarily mean homemade. In this sentence it simply refers to the toothpaste that was at home.

It means it had run out or it was already finished.

This part has two layers:

• imeisha = it has finished / it has run out
• ilikuwa imeisha = it had finished / it had run out

So this is like a past perfect idea in English: the toothpaste at home was already gone before the father bought more.

Because of noun-class agreement.

dawa belongs to noun class 9 in the singular, and the verb agrees with it using i-:

• ilikuwa
• imeisha

That agreement shows that the thing which had run out was dawa ya meno.

This is one of the most important features of Swahili grammar: verbs, adjectives, and other words often point back to a noun through agreement, so the noun does not always need to be repeated.