Learn Hardcore Swahili: Korido hii ni ndefu sana, na mwisho wake kuna bwawa la kuogelea. - This corridor is very long, and at its end there is a swimming pool.

Korido means corridor, hallway, or passage inside a building.
It is a borrowing from English (corridor), but it is widely understood and used in modern Swahili.

You might also see:

barabara ya ndani or njia ya ndani – more descriptive, literally internal road/path, but less common for a building hallway. In most everyday contexts, korido is perfectly natural.

Why is it korido hii and not something like huyu korido or hili korido?

Swahili demonstratives (this/that) must agree with the noun class:

korido belongs to noun class 9/10 (the class with many loanwords and names of things).
The class 9 form of this is hii.

So we say:

korido hii = this corridor not huyu korido (class 1, used for people)
and not hili korido (class 5, used with many ji-/Ø nouns).

Other forms with korido:

korido hii – this corridor (near the speaker)
korido hiyo – that corridor (near the listener or already mentioned)
korido ile – that corridor (far away / more distant).

What is the role of ni in Korido hii ni ndefu sana? Why not use iko or ina?

Ni here is the copula meaning is (linking the subject to an adjective or noun):

Korido hii ni ndefu sana = This corridor is very long.

We use:

ni
- adjective: Korido hii ni ndefu (This corridor is long.)
iko or ina to talk about existence or location:
- Korido hii iko hapa. (This corridor is here.)
- Korido hii ina madirisha mengi. (This corridor has many windows.)

So with an adjective like ndefu (long), ni is the normal choice.

Why is it ndefu and not refu after korido hii?

The basic adjective root is -refu, meaning long/tall.

Adjectives must also agree with the noun class:

For class 1 (person): mtu mrefu (a tall person)
For class 7 (thing): kitabu kirefu (a long book, e.g. in pages)

Korido is class 9, and in this class many adjectives take an n- prefix that often changes the first consonant of the adjective:

n-
- refu → ndefu

So:

korido ndefu = a long corridor
Similarly: barabara ndefu (a long road), nguo ndefu (a long dress).

Refu and ndefu express the same idea; the difference is just agreement with the noun class.

What does sana mean, and why does it come after ndefu?

Sana means very, a lot, so much.
It generally comes after the adjective, verb, or expression it intensifies:

ndefu sana – very long
anachelewa sana – he/she is very late / delays a lot
nimechoka sana – I am very tired

So Korido hii ni ndefu sana is literally This corridor is long very, which in natural English becomes This corridor is very long.

How does mwisho wake mean its end? What is wake?

Mwisho means end.
Wake is a possessive pronoun meaning his/her/its, but it is shaped to match the noun class of mwisho (class 3).

Structure:

mwisho – end
wa- – possessive prefix for class 3 nouns
-ke – 3rd person singular (his/her/its)

So mwisho wake literally = its end / his end / her end, depending on context.
Here, the context is korido hii, so we understand mwisho wake as the end of this corridor.

If you spell it out instead of using wake, you can say:

mwisho wa korido hii – the end of this corridor

What does kuna do in mwisho wake kuna bwawa?

Kuna is an existential verb meaning there is / there are.

Typical pattern:

Kuna bwawa – There is a pool.
Mwisho wake kuna bwawa – At its end, there is a pool.

You will often see:

kuna – there is/are (general, very common)
pana – there is/are at a specific place (more formal/literary)
mna – there is/are in/among (less common)

In everyday speech, kuna is used very widely, as in this sentence.

How is bwawa la kuogelea formed, and why do we use la?

Bwawa la kuogelea is literally a pool of swimming, i.e. a swimming pool.

Breakdown:

bwawa – pool, pond, dam
la – possessive/linking word for class 5 nouns (like bwawa) meaning of
kuogelea – to swim / swimming

So the structure is:

bwawa la X – pool of X
Examples:
bwawa la maji – pool of water
bwawa la samaki – fish pond
bwawa la kuogelea – swimming pool

How can kuogelea (to swim) also mean swimming here?

In Swahili, the ku- infinitive form of many verbs can function as a verbal noun—like -ing forms in English.

kuogelea – to swim / swimming
kupika – to cook / cooking
kusoma – to read / reading, to study / studying

So:

Ninapenda kuogelea. – I like to swim / I like swimming.
bwawa la kuogelea – a pool for swimming / a swimming pool.

Context tells you whether to read it as to swim or swimming in English.

Could we change the order and say Kuna bwawa la kuogelea mwisho wa korido hii? Would it still be correct?

Yes, that word order is also grammatically correct and natural:

Mwisho wake kuna bwawa la kuogelea.
– Focuses first on the end of the corridor, then tells us what is there.
Kuna bwawa la kuogelea mwisho wa korido hii.
– Starts with there is a swimming pool, then adds at the end of this corridor.

Both mean the same thing; the difference is just emphasis and flow of information.

What is the function of na in this sentence, and could we split it into two sentences instead?

Here na is a conjunction meaning and, linking two clauses:

Korido hii ni ndefu sana, na mwisho wake kuna bwawa la kuogelea.
= This corridor is very long, and at its end there is a swimming pool.

You could also make two separate sentences:

Korido hii ni ndefu sana. Mwisho wake kuna bwawa la kuogelea.

Both are correct. Using na simply joins the two related facts more smoothly, just like and in English.