Mama ni mkarimu, na Asha ni mtiifu, kwa hiyo nyumba yetu huwa tulivu.

Ni is the basic Swahili copula, the word used to link a subject with a description or identity. In English, it often corresponds to is or are.

• Mama ni mkarimu = Mother is generous.
• Asha ni mtiifu = Asha is obedient.

A useful thing to notice is that ni does not change the way English am / is / are do. In this kind of sentence, Swahili keeps ni the same.

Yes, here na means and.

Swahili na can mean both and and with, depending on context.

• Mama na Asha = Mother and Asha
• Ninakuja na Asha = I am coming with Asha

In your sentence, it is joining two clauses, so it clearly means and:

• Mama ni mkarimu, na Asha ni mtiifu = Mother is generous, and Asha is obedient

That m- is connected to noun class agreement for a singular person, especially class 1.

Since Mama and Asha are people, the descriptive words appear in the class 1 singular form:

• mkarimu = generous
• mtiifu = obedient

If you changed to a plural group of people, you would usually see wa- instead:

• Wao ni wakarimu = They are generous
• Watoto ni watiifu = The children are obedient

So the m- here helps show that the description belongs to one person.

Huwa shows a habitual or usual state. It means something like:

• is usually
• tends to be
• is generally

So:

• nyumba yetu huwa tulivu = our house/home is usually calm/peaceful

This is a little different from ni:

• nyumba yetu ni tulivu would sound more like a simple statement of quality: our house is calm
• nyumba yetu huwa tulivu emphasizes that this is the normal pattern or usual situation

So huwa is a very natural choice when the English meaning includes usually or generally.

Kwa hiyo means therefore, so, for that reason, or as a result.

It connects a cause to a result:

• Mama ni mkarimu, na Asha ni mtiifu, kwa hiyo nyumba yetu huwa tulivu.
• Mother is generous, and Asha is obedient, so our house is usually peaceful.

It is a very common linking expression in Swahili.

In Swahili, possessives usually come after the noun, not before it.

So:

• nyumba yetu = our house
• kitabu changu = my book
• watoto wetu = our children

The possessive part here is based on -etu = our, and it agrees with the noun class of nyumba, giving yetu.

So the word order is:

• noun + possessive

not

• possessive + noun

Because nyumba belongs to noun class 9/10, and with this class the agreeing form of some descriptive words may appear without a visible prefix.

So:

• nyumba tulivu = a calm house
• nyumba yetu huwa tulivu = our house is usually calm

With a singular person, you would often see a different form:

• mtoto mtulivu = a calm child

And with plural people:

• watoto watulivu = calm children

So tulivu is the right form here for nyumba.

Mama by itself can very naturally mean Mother or Mom, if the context makes it clear who is meant. Swahili often leaves that relationship understood.

• Mama ni mkarimu = Mother is generous / Mom is generous

If you want to make it explicitly my mother, you can say:

• Mama yangu ni mkarimu = My mother is generous

So the shorter Mama is not wrong; it just relies on context.

Swahili does not use articles like English a, an, and the.

That means a noun like mama or nyumba can be interpreted from context:

• mama = a mother / the mother / mother
• nyumba = a house / the house / house / home

So Swahili simply does not need separate words for articles in the way English does.

Yes, nyumba can be both singular and plural in form. This is normal for class 9/10 nouns.

So:

• nyumba can mean house or houses
• nyumba yetu can mean our house or our houses

Usually, context tells you which meaning is intended. Since the meaning has already been given to you as singular, you understand it here as our house. But grammatically, the form itself does not change.