Mbwa wetu hutikisa mkia wake watoto wanaporudi nyumbani.

Hutikisa comes from the verb -tikisa, which means shake. In this sentence, with mkia (tail), it is naturally understood as wag or shake the tail.

The prefix hu- marks a habitual action. So hutikisa means something like:

• usually shakes
• habitually shakes
• tends to shake / wag

So the sentence is not mainly describing one action happening right now. It describes what the dog typically does when that situation happens.

This is a noun-class agreement question.

Even though mbwa does not look like a typical class 1 noun on the surface, animals often take animate agreement in Swahili, especially in the singular. That is why the possessives appear as:

• wetu = our
• wake = his/her/its

So:

• mbwa wetu = our dog
• mkia wake = its tail

For a learner, the simplest way to remember this is:

• with a singular animate noun like mbwa, forms such as wetu, wake, wangu are normal

For example:

• mbwa wangu = my dog
• mbwa wake = his/her dog
• mbwa wetu = our dog

The difference is mainly one of habit versus current/ongoing action.

• hutikisa = usually wags / habitually wags
• anatikisa = is wagging or sometimes wags, depending on context

So in this sentence, hutikisa is a good choice because the sentence describes what the dog normally does whenever the children come home.

Compare:

• Mbwa wetu hutikisa mkia wake watoto wanaporudi nyumbani.
  Our dog usually wags its tail when the children come home.

• Mbwa wetu anatikisa mkia wake sasa.
  Our dog is wagging its tail now.

In standard Swahili, the habitual marker hu- is commonly used without the usual subject marker.

So you get patterns like:

• husoma = usually reads / usually study
• huja = usually comes
• hutikisa = usually shakes

This happens regardless of whether the subject is I, you, he/she, they, or a noun stated separately.

Examples:

• Mimi huenda = I usually go
• Watoto hucheza = Children usually play
• Mbwa hutikisa mkia = A dog usually wags its tail

So hutikisa is normal here.

Because the object is already stated directly after the verb:

• hutikisa mkia wake = shakes/wags its tail

In Swahili, an object marker is often not necessary when the object noun is expressed clearly in the sentence. The basic pattern is simply:

• verb + object noun

So:

• hutikisa mkia wake is perfectly normal

Object markers are more likely when the object is already known, emphasized, or represented by a pronoun-like idea. But here, just saying the noun phrase mkia wake is enough.

Wanaporudi can be broken down like this:

• wa- = they
• -na- = present tense
• -po- = relative marker here used for when
• -rudi = return / come back

So wanaporudi means roughly:

• when they return
• when they are returning

In natural English for this sentence, when they return is the best fit.

The important piece for learners is -po-, because it often gives the sense of when / where / at the time that, depending on context.

Not if you want the meaning when the children return home.

• watoto wanarudi nyumbani = the children are returning home / the children return home
• watoto wanaporudi nyumbani = when the children return home

So the -po- part is what turns the clause into a time clause here.

Without it, you are simply making a regular statement about the children returning.

Nyumbani means at home, home, or to home, depending on context.

The ending -ni is a very common locative ending in Swahili. It often gives a meaning like:

• in
• at
• to

So:

• nyumba = house
• nyumbani = at home / home

In this sentence, nyumbani is best understood as home:

• wanaporudi nyumbani = when they return home

Yes. Wake can mean:

• his
• her
• its

Swahili usually does not distinguish between his, her, and its in this form. The meaning is understood from context.

So in this sentence:

• mkia wake = its tail

because the possessor is mbwa wetu (our dog).

No. In this sentence, wanaporudi already expresses when they return.

So:

• watoto wanaporudi nyumbani = when the children return home

You can sometimes use wakati in other sentences, but it is not required here. The relative structure with -po- already does the job.

A learner-friendly way to think of it is:

• wanaporudi already contains the idea of when

Yes. The structure is natural:

• Mbwa wetu = subject
• hutikisa = verb
• mkia wake = object
• watoto wanaporudi nyumbani = time clause

So the whole pattern is:

• subject + verb + object + when-clause

That is a very normal way to build this kind of sentence in Swahili. A comma is sometimes added in writing before the time clause, but the grammar itself is fine either way.