Kitasa hiki kinahitaji kubadilishwa kwa sababu kimeharibika.

Because kitasa belongs to noun class 7 in Swahili, and words that relate to it must agree with that class.

So in this sentence:

• kitasa = the noun
• hiki = this for class 7 singular nouns
• ki-nahitaji = it needs
• ki-meharibika = it has become damaged / it is damaged

This agreement system is one of the most important parts of Swahili grammar.

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

So:

• kitasa hiki = this lock
• mlango huu = this door
• kiti hiki = this chair

That is the normal pattern: noun + demonstrative

Kitasa usually refers to a lock, latch, or locking part of a door or gate, depending on context.

In many real situations, English might translate it as:

• lock
• door lock
• latch

The exact English word depends on what kind of object is being discussed.

Kinahitaji can be broken down like this:

• ki- = subject prefix for noun class 7 singular
• -na- = present tense marker
• -hitaji = need

So kinahitaji literally means:

• it needs
• or more word-for-word, it is needing

In normal English, we say it needs.

Because kubadilishwa is the passive form.

Breakdown:

• ku- = infinitive marker, like to
• -badilisha = change
• -w- = passive extension
• kubadilishwa = to be changed

So:

• kubadilisha = to change something
• kubadilishwa = to be changed

In this sentence, the lock is receiving the action, not doing it, so the passive makes sense: the lock needs to be changed

It can mean either, depending on context.

Literally, kubadilishwa means to be changed. But in real-life English, when talking about a broken lock, the most natural meaning is often:

• to be replaced

So even if the Swahili says changed, the practical meaning may be replaced with another one.

Kwa sababu means because.

It is a very common fixed phrase in Swahili.

Examples:

• Nimechelewa kwa sababu ya trafiki. = I am late because of traffic.
• Anaondoka kwa sababu amechoka. = He/she is leaving because he/she is tired.

In your sentence:

• kwa sababu kimeharibika = because it is damaged / because it has broken

Kimeharibika can be broken down like this:

• ki- = subject prefix for class 7 singular
• -me- = perfect marker
• -haribika = become damaged, become spoiled, break down

So kimeharibika means something like:

• it has become damaged
• it has broken
• it is damaged

The perfect tense here often describes a present result of a completed change.

This is a very useful contrast.

• -haribu = damage something, spoil something, break something
  → usually transitive: someone damages something
• -haribika = become damaged, get spoiled, break down
  → usually intransitive: the thing itself ends up damaged

Compare:

• Ameharibu kitasa. = He/she has damaged the lock.
• Kitasa kimeharibika. = The lock has become damaged / is broken.

So in your sentence, kimeharibika is used because the sentence describes the lock’s condition, not who caused it.

Because -me- and -li- do different jobs.

• kimeharibika = it has become damaged / it is now damaged
• kiliharibika = it became damaged / it got damaged at some point in the past

The form with -me- often emphasizes the current result. That fits this sentence well, because the lock now needs changing.

So the logic is:

• it has become damaged
• therefore it needs to be changed

Because Swahili normally does not have articles like English a/an/the.

Whether something is understood as:

• a lock
• the lock
• this lock

depends on context or on other words.

Here, hiki already makes it specific:

• kitasa hiki = this lock

So no separate word for the is needed.

Yes. That would also be natural.

Compare:

• Kitasa hiki kinahitaji kubadilishwa. = This lock needs to be changed.
• Kitasa hiki lazima kibadilishwe. = This lock must be changed.

The difference is tone:

• kinahitaji kubadilishwa = needs to be changed
  slightly descriptive, practical
• lazima kibadilishwe = must be changed
  stronger, more forceful

Both are correct, but the original sentence sounds a bit more neutral.

Because in Swahili, the subject is often built directly into the verb.

So:

• ki-nahitaji already means it needs
• ki-meharibika already means it has become damaged / it is damaged

The ki- part carries the idea of it, specifically it referring to a class 7 noun like kitasa.

This is why Swahili verbs often contain a lot of information in one word.