Learn Hardcore Swahili: Walimu walieleza kwamba lahaja zote za Kiswahili ni muhimu katika utamaduni wetu. - The teachers explained that all Swahili dialects are important in our culture.

Walimu – teachers (plural of mwalimu, teacher).
walieleza – (they) explained.
- wa- – subject prefix for they (people, noun class 2)
- -li- – past tense marker (did)
- -eleza – verb root explain
kwamba – that (introduces a subordinate clause).
lahaja – dialects (here used as plural from context; standard plural: lahaja or lahaja za...).
zote – all (agreeing with lahaja, noun class 10).
za – of (possessive/associative for noun class 10).
Kiswahili – Swahili (language).
ni – are/is (copula; here “are”).
muhimu – important.
katika – in/within.
utamaduni – culture.
wetu – our.

Full sense: “The teachers explained that all dialects of Swahili are important in our culture.”

Why do both walimu and walieleza start with wa-? Are they related?

Yes, they are related, but they play different roles:

In walimu, wa- is a noun class prefix that marks plural for people (class 2), so mwalimu (teacher) → walimu (teachers).
In walieleza, wa- is the subject prefix on the verb, meaning they (for class 2 nouns like walimu).

So:

Walimu walieleza... literally: Teachers they-explained...
The matching wa- shows subject–verb agreement in Swahili.

What exactly is the tense and structure of walieleza?

Walieleza is:

wa- – subject prefix for they (class 2, people).
-li- – past tense marker (simple past).
-eleza – verb root meaning explain.

So walieleza = they explained / they did explain, in the simple past tense.

What is the difference between walimu and mwalimu?

They are singular vs plural:

mwalimu – a teacher, the teacher (singular, noun class 1).
walimu – teachers, the teachers (plural, noun class 2).

Swahili often uses m-/mw- for singular people and wa- for their plural:

mtoto → watoto (child → children)
mwalimu → walimu (teacher → teachers)

What does kwamba do here? Could we leave it out?

Kwamba is a conjunction meaning that, introducing a clause:

Walimu walieleza kwamba ...
= The teachers explained that ...

You can sometimes drop kwamba, especially in more informal speech, and say:

Walimu walieleza lahaja zote za Kiswahili ni muhimu...

This is still understandable, but kwamba is clearer and more standard in careful or written Swahili, especially when the clause is longer or complex.

Why is it lahaja zote za Kiswahili and not zote lahaja za Kiswahili?

In Swahili, quantifiers like zote (all) normally come after the noun they modify:

lahaja zote – all dialects
vitabu vyote – all books
siku zote – all days / always

So the natural order is:

lahaja zote za Kiswahili – all dialects of Swahili

Putting zote before the noun (zote lahaja) would be ungrammatical in standard Swahili.

Why is it zote and not ote?

Zote is the form of ote (all) that agrees with lahaja, which belongs to noun class 10 (and also class 9 for singular).

Agreement pattern:

Class 1 (mtu) – ote → yote
Class 2 (watu) – ote → wote
Class 9/10 (lahaja) – ote → zote

So:

lahaja zote – all dialects
because lahaja is class 9/10 and takes the z- agreement.

Why is it za Kiswahili and not ya Kiswahili or wa Kiswahili?

The form of “of” (the associative) has to agree with the first noun (lahaja):

lahaja – class 9/10 → associative za

So:

lahaja za Kiswahili – dialects of Swahili

Compare with other classes:

kitabu cha Kiswahili – a Swahili book (kitabu, class 7 → cha)
vitabu vya Kiswahili – Swahili books (vitabu, class 8 → vya)
watu wa Kiswahili – Swahili people (watu, class 2 → wa)

Here lahaja is class 9/10, so za is the correct associative form.

Why do we use ni before muhimu? Can we just say lahaja ... muhimu?

Ni here is the copula meaning is/are:

lahaja zote za Kiswahili ni muhimu
= all dialects of Swahili are important

In Swahili, the copula ni is usually needed between the subject and a predicate noun or adjective (like muhimu):

Mti huu ni mrefu – This tree is tall.
Walimu ni wachache – The teachers are few.

You might sometimes hear ni dropped in very casual speech, but the correct standard form here is to include ni.

Does muhimu change form to agree with lahaja zote?

No. Muhimu is one of those adjectives that does not change for different noun classes (it’s “invariable”):

mtu muhimu – an important person
watu muhimu – important people
lahaja muhimu – an important dialect
lahaja zote muhimu – all important dialects

So muhimu stays the same with singular or plural, any class.

What is the difference between katika utamaduni wetu and just utamaduni wetu?

utamaduni wetu – our culture
katika utamaduni wetu – in our culture / within our culture

Katika is a preposition meaning in / inside / within.
So katika utamaduni wetu emphasizes that within the context of our culture, these dialects are important, not just as an abstract statement.

Why is it utamaduni wetu (with wetu) and not yetu?

The possessive our must agree with the noun class and prefix of the noun:

utamaduni is class 11/14 with prefix u-.
For this class, “our” takes the form wetu.

So:

utamaduni wetu – our culture
mji wetu – our town (mji, class 3/4 → wetu)
kitabu chetu – our book (kitabu, class 7 → chetu)
vitabu vyetu – our books (vitabu, class 8 → vyetu)

Using yetu here would be incorrect because yetu is for class 9/10 nouns like nyumba yetu (our house).