Polisi walisema kwamba mtu huyo hatapelekwa kwenye gereza mpaka mahakama iamue.

Yes. Polisi can refer to one police officer or to the police as a group. The verb tells you which meaning is intended.

Here, walisema breaks down as:

• wa- = they
• -li- = past tense
• -sema = say

So polisi walisema means the police said or police said.
If it referred to one officer, you would expect polisi alisema.

Walisema means they said.

Its parts are:

• wa- = subject marker for they
• -li- = past tense marker
• -sema = verb root say / speak

So Swahili often packs subject + tense + verb into one word. That is why walisema already includes the idea of they.

Kwamba means that and introduces a reported clause, just like English in They said that...

So:

• Polisi walisema kwamba... = The police said that...

In some contexts, especially casual speech, kwamba may be omitted after sema, but it is very common and very natural to include it, especially in careful, formal, or written Swahili.

Huyo is a demonstrative, here meaning something like that.
So mtu huyo means that person.

In real usage, huyo often refers to someone already mentioned or known from context. In news-style language, mtu huyo can sound like that person or the person in question.

So even if English translation uses the person, Swahili often uses a demonstrative where English might not.

Swahili does not have articles that work exactly like English the and a/an.

Instead, definiteness is usually shown by:

• context
• demonstratives like huyu, huyo, yule
• possessives
• other markers in the sentence

So mtu huyo feels definite because huyo points to a specific person: that person / the person in question.

Likewise, mahakama can be understood as the court from context, even though there is no separate word for the.

Hatapelekwa means he/she will not be taken or will not be sent.

It can be broken down as:

• ha- = negative subject marker for he/she
• -ta- = future tense
• -pelek- = verb root from kupeleka = to take / carry / send
• -wa = passive ending

So literally it is something like:

he/she-not-will-be-taken

Because the subject is mtu huyo, the full sense is that person will not be taken.

The passive is used because the sentence focuses on the person, not on who will take them.

English does this too:

• The person will not be taken to prison...
  rather than
• They will not take the person to prison...

A Swahili active version could be something like:

Polisi hawatampeleka mtu huyo kwenye gereza...

But the passive hatapelekwa is very natural, especially in formal or news-style language, where the important point is what will happen to the person.

Kwenye gereza means to the prison, in prison, or more naturally in English, often just to prison, depending on context.

Here, because the verb is pelekwa (be taken), it clearly marks destination:

• kwenye gereza = to prison / to the prison

Kwenye is a locative word that can mean in, at, on, to, depending on the verb and context.

You may also hear gerezani, which is another natural way to say in/to prison. So:

• kwenye gereza
• gerezani

can both be correct, though they are formed differently.

Here mpaka means until.

So:

• hatapelekwa kwenye gereza mpaka mahakama iamue
  = he/she will not be taken to prison until the court decides

Because the main clause is negative, English often feels like not until:

• will not be taken to prison until the court decides

So mpaka does not mean before here. It marks the point up to which something will not happen.

This is because Swahili often uses the subjunctive after mpaka when talking about something that has not happened yet and must happen before the main action can happen.

So:

• mahakama iamue = until the court decides

The form iamue is subjunctive, not plain future.

If you said mahakama itaamua, that would be a straightforward future statement: the court will decide. That form is possible in other contexts, but after mpaka in a sentence like this, the subjunctive iamue is the more natural choice.

Because mahakama takes noun-class agreement that uses i- in the singular.

So in iamue:

• i- = subject marker agreeing with mahakama
• -amue = subjunctive form of amua (decide)

This may feel strange to an English speaker because mahakama refers to a court, which sounds like an institution made of people. But in Swahili, agreement follows noun class, not natural gender in the English sense.

So:

• mahakama iamue = the court decide / more natural English: the court decides

Sometimes yes, but the meaning would shift slightly.

• huyo often refers to someone near the listener, or someone already under discussion
• yule often points to someone more distant, physically or mentally

In news and formal reporting, huyo is very commonly used for the said person / that person just mentioned. So mtu huyo is a very natural choice here.

If you changed it to mtu yule, it would sound more like that person over there / that particular person, with a stronger distancing effect.