Learn Hardcore Swahili: Saa ya ukutani ilipiga mara tatu, tukajua ni saa tisa kamili. - The wall clock struck three times, and we knew it was exactly three o'clock.

“ya” is the possessive form that agrees with the noun saa, which is in noun class 9/10.
For class 9/10 nouns, the possessive marker is ya (not wa, la, etc.). So:

saa ya ukutani = clock of the wall (wall clock)
You cannot say saa wa ukutani here; that would be ungrammatical, because wa is for different noun classes (1/2).

What is going on with “ukutani”? Why not just “ukuta”?

ukuta = wall
Adding -ni makes it a locative (a place): ukutani = “on the wall / at the wall”.

So:

saa ya ukuta – more like “the clock of the wall” (grammatical, but less natural)
saa ya ukutani – “the clock that is on the wall” → simply wall clock

The -ni suffix is common with place-like meanings:

mezani – on/at the table (from meza = table)
nyumbani – at home (from nyumba = house)
kanisani – at church (from kanisa = church)

Why does the verb look like “ilipiga”? How is that formed?

ilipiga comes from piga = to hit/strike. It’s conjugated:

i- : subject prefix for class 9 nouns (here: saa, “clock”)
-li- : past tense marker (simple past)
piga : verb stem

So:

saa ilipiga = literally “the clock it-past-struck” → “the clock struck / chimed”.

For a human subject in class 1, you’d see:

mtu alipiga – the person hit/struck

Why does “ilipiga” mean “struck/chimed” here instead of just “hit”?

In Swahili, piga is very versatile and is used in many fixed expressions. Some relevant ones:

saa inapiga – the clock strikes/chimes
piga ngoma – play the drum (literally “hit the drum”)
piga simu – to phone someone (literally “hit a call”)

So in the context of a clock, ilipiga is understood as “(the clock) struck” or “(the clock) chimed.”
You don’t need to add another word like “kengele” (bell); the context is clear.

What does “mara tatu” mean, and how do you say “once, twice, three times” in Swahili?

mara = time/occasion (as in “times you do something”)
tatu = three

So mara tatu = three times.

The common pattern is:

mara moja – once (one time)
mara mbili – twice (two times)
mara tatu – three times
mara nyingi – many times / often

In the sentence, ilipiga mara tatu = “it struck three times.”

What does “tukajua” mean exactly, and how is it different from “tulijua”?

tukajua is built like this:

tu- : “we” (subject prefix, person 1 plural)
-ka- : the -ka- tense/aspect, often called the “sequential” or narrative ka-
jua : to know

So tukajua = “and then we knew / so we knew / and we came to know.”

Difference from tulijua:

tulijua (tu- + -li- + jua) – plain past: “we knew.”
tukajua – links more tightly to the previous action and often implies consequence or sequence:
“The clock struck three times, so we knew it was nine o’clock sharp.”

The -ka- here gives a sense of “and then / as a result,” not just a neutral past action.

Why is there no separate word for “we” in “tukajua”?

In Swahili, the subject is normally built into the verb as a prefix:

tu- = we
u- = you (singular)
a- = he/she
wa- = they (for people, class 2)
ni- = I

So:

tukajua already means “we (then) knew.”
Adding sisi (we) is only for emphasis:
- Sisi tukajua… = we (as opposed to others) then knew…

That’s why there’s no separate “we” word in the sentence; it’s already encoded in tu-.

In “tukajua ni saa tisa kamili”, what is the role of “ni”?

ni is the copula (“to be”) used to link a subject and a complement:

Ni mwalimu. – He/She is a teacher.
Hii ni saa. – This is a clock.

In tukajua ni saa tisa kamili, the literal structure is something like:

“we-then-knew (that it) is nine o’clock exactly.”

Even though the context is past, ni itself doesn’t change for tense here; Swahili often uses ni for timeless or context-determined “to be.”
The pastness is already given by tukajua (“we came to know”).

A more explicit but longer version would be:

tukajua kwamba ilikuwa saa tisa kamili – we knew that it was exactly nine o’clock.

What does “saa tisa” refer to? Is it 9:00 the way English speakers say it?

In Swahili, especially in East Africa, clock hours are usually counted from about 6:00 a.m. (sunrise) as saa 12 / saa sita usiku becoming saa 12 / saa sita vs then saa 1 asubuhi (around 7 a.m.). A common teaching simplification:

saa moja ≈ 7:00
saa mbili ≈ 8:00
…
saa tisa ≈ 3:00 p.m.

So saa tisa in local Swahili time is what English speakers would call three o’clock.

However, in some teaching contexts or simplified materials, saa tisa might be glossed as “nine o’clock” if they are using “European” numbering directly. The sentence you gave is likely assuming that direct 1–12 mapping (1 = 1, 2 = 2, 9 = 9).
In real-life Swahili, be aware of this “Swahili clock” difference.

What does “kamili” add to the meaning in “saa tisa kamili”?

kamili means “complete, exact, full.”

When used with time:

saa tisa kamili – exactly nine o’clock / nine o’clock on the dot
saa mbili kamili – exactly two o’clock
saa saba kamili – exactly seven o’clock

It emphasizes that it is right on the hour, not earlier or later.
Compare with other time phrases:

saa tisa na robo – nine fifteen (nine and a quarter)
saa tisa kasoro robo – quarter to nine

Why is there a comma before “tukajua” instead of using “na” (“and”)?

The sentence:

Saa ya ukutani ilipiga mara tatu, tukajua ni saa tisa kamili.

is really two actions in sequence:

The wall clock struck three times.
We (then) knew it was exactly nine o’clock.

The -ka- in tukajua already carries a sense of “and then / so”, so an extra na (“and”) is not necessary. Writing:

Saa ya ukutani ilipiga mara tatu na tukajua…

would be understandable but slightly heavier; the comma plus -ka- does the linking job very naturally.

Could I say “tulijua kwamba ilikuwa saa tisa kamili” instead of “tukajua ni saa tisa kamili”? What’s the difference?

Yes, you can say:

Saa ya ukutani ilipiga mara tatu, tulijua kwamba ilikuwa saa tisa kamili.

Differences in feel:

tukajua ni saa tisa kamili
- More compact, everyday style
- -ka- gives a narrative/“then we knew” feeling
- Omits kwamba (“that”), which is very natural in speech
tulijua kwamba ilikuwa saa tisa kamili
- Slightly more formal/explicit
- Uses kwamba (“that”), and ilikuwa (past of “be”)
- Feels like a more careful, written explanation

Both are correct; the original is just more colloquial and efficient.