Mimi ninasona shati jipya nyumbani.

Because Swahili often puts the subject inside the verb itself.

In ninasona:

• ni- = I
• -na- = present tense
• -sona = the verb stem

So ninasona already tells you the subject is I.

That means mimi is usually added for emphasis, contrast, or extra clarity.
So:

• Ninasona shati jipya nyumbani = a neutral I am sewing a new shirt at home
• Mimi ninasona shati jipya nyumbani = I am sewing a new shirt at home, perhaps stressing that it is me, not someone else

It is made of several pieces joined together:

• ni- = I
• -na- = present tense
• -sona = sew

So ninasona literally works like:

I + present + sew

That is why one Swahili verb can express what takes several words in English.

It can mean either one, depending on context.

The tense marker -na- is commonly used for the present in Swahili, and English may translate it as:

• I sew
• I am sewing

In a sentence like Mimi ninasona shati jipya nyumbani, English will often choose I am sewing a new shirt at home, because it sounds like an action happening now. But in another context, it could also be understood more generally.

Because in Swahili, adjectives usually come after the noun.

So:

• shati = shirt
• jipya = new

Together:

• shati jipya = new shirt

This is a very common pattern in Swahili:

• mtoto mdogo = small child
• kitabu kikubwa = big book
• shati jipya = new shirt

Because adjectives in Swahili must agree with the noun class of the noun they describe.

Here, shati behaves like a singular noun that takes the agreement form ji- for this adjective, so -pya becomes:

• jipya = new

This agreement is very important in Swahili grammar.

For example:

• shati jipya = new shirt
• mashati mapya = new shirts

Notice how the adjective changes from jipya to mapya when the noun becomes plural.

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

So shati jipya can mean:

• a new shirt
• the new shirt

The exact meaning depends on context.

This is very normal in Swahili. Learners often want to add an article because English requires one, but Swahili does not.

Because nyumbani already has a locative meaning, roughly at home or home.

It comes from nyumba = house/home, with a locative ending that gives the idea of location.

So:

• nyumba = house
• nyumbani = at home / in the house / home

That is why Swahili does not need a separate word like English at in this sentence.

The basic order here is:

subject + verb + object + place

So:

• Mimi = subject
• ninasona = verb
• shati jipya = object
• nyumbani = place

This is quite close to normal English word order:

I am sewing a new shirt at home

That makes this sentence feel relatively straightforward for an English speaker.

Yes. In fact, that is often the more natural neutral sentence.

Because the verb already contains the subject marker ni- for I, Swahili often drops the separate subject pronoun unless it is needed for emphasis.

So both are possible:

• Ninasona shati jipya nyumbani = neutral
• Mimi ninasona shati jipya nyumbani = more emphatic

Usually at home is the most natural translation, but the exact sense depends on context.

Nyumbani can refer generally to being at home, not just physically inside a building. In some situations, it could also be understood more literally as in the house or at the house, but at home is usually the best everyday choice.