Mji huu uko kusini mwa nchi.

A word-by-word breakdown is:

• mji = town or city
• huu = this (agreeing with mji)
• uko = is located / is
• kusini = south
• mwa = a linker here meaning something like of
• nchi = country

So the whole sentence means This town/city is in the south of the country or This town/city is south in the country, depending on how naturally you want to phrase it in English.

Because Swahili demonstratives must agree with the noun class of the noun they describe.

Mji belongs to the m-/mi- noun class pair:

• singular: mji
• plural: miji

For singular mji, the correct this form is huu.

So:

• mji huu = this town/city
• miji hii = these towns/cities

An English speaker often expects one single word for this, but in Swahili it changes depending on the noun class.

Uko is the form used to say something like is located or is in a place.

Here it agrees with mji, which is singular in the m-/mi- class, so it begins with u-.

So:

• mji huu uko... = this town is located...

It is not just a random word for is. In Swahili, location is often expressed with special forms like uko, rather than using ni.

Because ni is usually used to identify or equate things, not to show location.

For example:

• Huyu ni mwalimu = This person is a teacher

But in your sentence, the idea is location:

• Mji huu uko kusini mwa nchi = This town is in the south of the country

If you used ni here, it would sound like you were saying the town is the south of the country, not that it is located in the south.

It means in the south of the country or south of the country, depending on context.

Breakdown:

• kusini = south
• mwa nchi = of the country

So the whole phrase means the town is located in the southern part of the country.

With words like kaskazini (north), kusini (south), mashariki (east), and magharibi (west), Swahili often uses mwa before the larger place:

• kaskazini mwa Tanzania = in the north of Tanzania
• kusini mwa nchi = in the south of the country

Here, mwa is a linking word that works a bit like of in English.

So:

• kusini mwa nchi = the south of the country

You do not need to translate it literally every time. It is best to learn it as part of a common pattern used after direction words like:

• kaskazini mwa... = north of...
• kusini mwa... = south of...
• mashariki mwa... = east of...
• magharibi mwa... = west of...

In Swahili, demonstratives like this usually come after the noun.

So:

• mji huu = this town
• kitabu hiki = this book
• watoto hawa = these children

This is one of the basic word-order differences from English. English says this town; Swahili usually says town this.

It can mean either town or city, depending on context.

In everyday Swahili, mji is often used quite broadly for an urban settlement. If you want to be more specifically city, Swahili also has jiji.

So depending on context:

• Mji huu uko kusini mwa nchi could be translated as
  This town is in the south of the country
  or
  This city is in the south of the country

Mji is singular in the m-/mi- noun class pair:

• singular: mji
• plural: miji

That noun class affects agreement words in the sentence:

• mji huu → huu agrees with mji
• mji huu uko → u- in uko also agrees with mji

So a lot of the sentence shape is controlled by the noun class of mji.

This is a major feature of Swahili grammar: words connected to a noun often change form to match that noun’s class.

You would say:

Miji hii iko kusini mwa nchi.

Changes:

• mji → miji = town/city → towns/cities
• huu → hii = this → these
• uko → iko = agreement changes for the plural noun class

So:

• Mji huu uko kusini mwa nchi. = This town is in the south of the country.
• Miji hii iko kusini mwa nchi. = These towns are in the south of the country.

In real usage, learners may also come across forms like upo or umo in other location sentences, because Swahili has several locative forms.

But for this sentence, uko is a very natural and standard way to say is located.

A simple learner-friendly way to think about it is:

• use uko for general location

So Mji huu uko kusini mwa nchi is a good model sentence to learn and use.