Kiboko yuko mtoni karibu na mamba.

Because yuko is used to say where someone or an animal is. It means something like is located / is there.

By contrast, ni is used to identify or classify something:

• Kiboko ni mnyama = The hippo is an animal
• Kiboko yuko mtoni = The hippo is in the river

So in this sentence, yuko is the natural choice because the sentence is about location.

That is a very common question. Even though kiboko has the shape of a ki-/vi- noun, animals are often treated with animate agreement in Swahili, especially when talking about them as living beings.

So:

• yuko = animate singular, used naturally for an animal here

A learner can think of it this way: when the noun refers to a living creature, Swahili often uses the same agreement pattern it uses for people.

Mtoni means in the river, at the river, or by the river, depending on context.

It comes from:

• mto = river
• -ni = a locative ending meaning in / at / on / by

So:

• mto → mtoni

In this sentence, because a hippo is involved, the most natural meaning is in the river.

Not always. The locative ending -ni is broader than English in.

Depending on context, it can mean:

• in
• at
• on
• by

So mtoni could mean in the river, at the river, or by the river. English usually has to choose one, but Swahili often leaves that a bit more flexible.

Karibu na means near or close to.

In this sentence:

• karibu na mamba = near the crocodile or near crocodiles

The phrase works as a unit:

• karibu = near/close
• na = connects it to the thing that is near

It often does mean and or with, but here it is part of the fixed expression karibu na, meaning near to.

So in this sentence, do not translate na by itself as and. Read the whole phrase together:

• karibu na mamba = near the crocodile / near crocodiles

It can be either. Mamba has the same form in the singular and the plural.

So:

• mamba can mean crocodile
• mamba can also mean crocodiles

Only context tells you which one is meant. In a longer sentence, agreement elsewhere might make the number clearer.

Because Swahili does not use articles the way English does.

So:

• kiboko can mean a hippo or the hippo
• mamba can mean a crocodile, the crocodile, or crocodiles

Context tells you whether the meaning is definite or indefinite.

The word order is:

subject + location verb + place + extra location phrase

So:

• Kiboko = subject
• yuko = is located
• mtoni = in the river
• karibu na mamba = near the crocodile / near crocodiles

This is a very normal Swahili sentence pattern.

Yes, if it is already clear from context.

You could say:

• Yuko mtoni karibu na mamba.

That would mean He/She/It is in the river near the crocodile(s), with an animate subject understood from context.

But when you first introduce the subject, keeping kiboko in the sentence is clearer.

It is pronounced roughly m-TO-ni, with the stress on TO.

The initial m is really pronounced. It can sound like a short syllabic m before to.

More broadly, the sentence has penultimate stress, which is common in Swahili:

• ki-BO-ko
• YU-ko
• m-TO-ni
• ka-RI-bu
• MAM-ba

Not always. Kiboko can also mean whip in other contexts.

But in this sentence, because of yuko mtoni karibu na mamba, the meaning is clearly hippo. The location and the nearby crocodile make the animal meaning the natural one.