Kama wangekuwa wameleta kokoto na chokaa mapema, ukuta ungekuwa umekamilika tayari.

It is a past counterfactual conditional, similar to the English third conditional:

If they had brought gravel and lime/cement early, the wall would already have been completed.

The idea is that this did not happen in reality. They did not bring the materials early, so the wall was not completed as expected.

Yes. That is the normal implication.

With Kama wangekuwa wameleta ... ukuta ungekuwa umekamilika tayari, the speaker is imagining an unreal past situation. So the listener understands:

• they did not bring the materials early
• therefore the wall was not completed already

It has two parts:

• wangekuwa = wa-

  • -nge-
    • -kuwa
  • wa- = they
  • -nge- = conditional marker
  • -kuwa = be

• wameleta = wa-

  • -me-
    • leta
  • wa- = they
  • -me- = perfect/completed action
  • leta = bring

Together, wangekuwa wameleta literally works something like they would be having brought, but in natural English it means they had brought in this kind of conditional sentence.

This is a common Swahili way to express an unreal past condition.

Because wameleta by itself means they have brought or they brought in a completed sense. It describes a real completed action.

But the sentence is not describing a real past event. It is describing a hypothetical past situation. That is why Swahili adds the conditional idea with -nge- and the auxiliary kuwa:

• wameleta = they have brought
• wangekuwa wameleta = if they had brought

So the longer form is what makes the clause clearly unreal/counterfactual.

Again, it has two parts:

• ungekuwa = u-

  • -nge-
    • -kuwa
  • u- = subject agreement for ukuta
  • -nge- = conditional
  • -kuwa = be

• umekamilika = u-

  • -me-
    • kamilika
  • u- = subject agreement for ukuta
  • -me- = perfect/completed state
  • kamilika = be finished / become complete

So ungekuwa umekamilika means it would have been finished / completed.

Because kamilika and kamilisha are related but different:

• kamilika = be complete / get finished
• kamilisha = complete / finish something
• kamilishwa = be completed (passive of kamilisha)

So:

• ukuta umekamilika = the wall is finished / has become complete
• ukuta umekamilishwa = the wall has been completed

In this sentence, umekamilika sounds natural because it focuses on the wall’s finished state.
If you used umekamilishwa, the meaning would still be possible, but it would sound a bit more explicitly passive.

Because ukuta takes u- subject agreement in the singular.

That is why you get:

• ungekuwa
• umekamilika

In Swahili, verbs must agree with the noun class of the subject. So the form of the verb changes depending on the noun it refers to.

• mapema = early / earlier / in good time
• tayari = already

So the sentence contrasts two time ideas:

• mapema tells us when the materials should have been brought
• tayari tells us the expected result by now or by that point: the wall would already be finished

Yes, to some extent.

This sentence begins with the if-clause:

Kama wangekuwa wameleta kokoto na chokaa mapema, ukuta ungekuwa umekamilika tayari.

But you could also put the result first:

Ukuta ungekuwa umekamilika tayari kama wangekuwa wameleta kokoto na chokaa mapema.

That still means the same thing.

Also, adverbs like tayari can sometimes move slightly, although the original order is very natural.

Because Swahili usually builds the subject into the verb.

In wangekuwa and wameleta, the prefix wa- already means they.

So Swahili does not need a separate pronoun unless you want emphasis:

• wao wangekuwa wameleta ... = they, specifically, had brought ...

Without wao, the sentence is still complete and normal.

You may hear shorter conditional forms, but they are not as precise for this exact meaning.

The fuller version:

Kama wangekuwa wameleta ..., ukuta ungekuwa umekamilika ...

very clearly expresses:

• an unreal event in the past
• an unreal result in the past

A shorter form like wangeleta / ungekamilika can sound more general or less explicitly tied to the had done / would have happened meaning. So the longer form is a good model when you want to express a clear past counterfactual.

In a building context:

• kokoto = gravel / small stones / aggregate
• chokaa = usually lime, though in some contexts learners may associate it with building material more generally

Depending on region and context, building vocabulary can vary a bit. If someone wanted to say cement very specifically, saruji is often the clearer word. But in this sentence, kokoto na chokaa clearly refers to construction materials needed for the wall.

Very often, yes. In this sentence, kama means if.

But kama can also mean like / as in other contexts, so learners need to rely on the sentence around it.

Here, because it introduces a condition, the meaning is definitely if:

Kama wangekuwa wameleta ... = If they had brought ...