Mama huongeza siki kidogo kwenye kachumbari, na mimi hula mtindi baada ya chakula cha mchana.

hu- marks the habitual aspect in Swahili. It tells you that something happens regularly, usually, or as a general habit.

So:

• Mama huongeza siki kidogo... = Mother usually adds a little vinegar...
• mimi hula mtindi... = I usually eat yogurt...

This is different from a form with -na-, which often suggests something happening now or a more neutral present depending on context.

Because ku- in kula is the infinitive marker, like to in English to eat.

So:

• kula = to eat
• the actual verb stem is -la

When you conjugate the verb, you normally drop the infinitive ku-:

• hula = usually eats / eat
• not hukula

The same idea applies to kuongeza:

• kuongeza = to add
• stem: -ongeza
• huongeza = usually adds

In this habitual hu- form, the verb itself does not show the subject as clearly as forms like ninakula or anakula do.

So mimi hula is used to make the subject explicit: I usually eat.

Also, in this sentence na mimi has a natural contrastive feel:

• Mama does one thing, and I do another.

So mimi is both useful and natural here.

siki kidogo means a little vinegar or a small amount of vinegar.

In Swahili, descriptive words usually come after the noun, not before it.

So:

• siki kidogo = vinegar little = a little vinegar

kidogo can mean:

• small/little with nouns
• a little / slightly in other contexts

Here it is describing the amount of vinegar.

kwenye is a locative word. Depending on context, it can mean:

• in
• on
• at
• sometimes to / into

Here, with ongeza (add), it is best understood as:

• to the kachumbari
• or literally in/into the kachumbari

So:

• huongeza siki kidogo kwenye kachumbari = usually adds a little vinegar to the kachumbari

baada ya means after.

It is a very common expression, and you can think of it as a set phrase:

• baada ya chakula cha mchana = after lunch
• baada ya kula = after eating

The ya links baada to what follows. So it is best learned as one chunk:

• baada ya = after

chakula cha mchana literally means food/meal of the daytime/afternoon, which is how Swahili expresses lunch.

Breakdown:

• chakula = food / meal
• mchana = daytime / afternoon
• cha = a linking word meaning something like of

So:

• chakula cha mchana = midday meal = lunch

The form cha is used because it agrees with chakula, which belongs to a particular noun class in Swahili.

Swahili uses different linking forms depending on the noun class of the first noun.

Here, chakula belongs to the class that takes cha.

So:

• chakula cha mchana = meal of midday

If the noun belonged to a different class, the linker would change. This is a normal part of Swahili grammar called agreement.

So cha is not random—it matches chakula.

Swahili generally does not use articles the way English does.

So a noun like mtindi can mean:

• yogurt
• the yogurt
• sometimes some yogurt

The exact meaning depends on context.

Likewise:

• siki kidogo = a little vinegar / some vinegar

English needs articles much more than Swahili does.

It can mean both, depending on context.

In this sentence, na means and because it joins two parts of the sentence:

• Mama huongeza... , na mimi hula...

In other sentences, na can mean with:

• chai na maziwa = tea with milk
• ninaenda na mama = I am going with mother

So you have to use context to tell which meaning is intended.

Yes, you could, but the nuance changes.

• huongeza / hula = usually does, habitually does
• anaongeza / ninakula = often more like is adding / am eating, though these forms can also sometimes be used more generally depending on context

So if you want to emphasize a routine or custom, huongeza and hula are especially good choices.

In other words:

• Mama huongeza... = Mom usually adds...
• Mama anaongeza... = Mom is adding... / Mom adds...

The sentence you were given sounds like it is talking about habitual behavior.