Leo asubuhi, nilinunua papai moja na tufaha mbili sokoni.

A rough word-by-word breakdown is:

• Leo = today
• asubuhi = morning
• nilinunua = I bought
• papai = papaya
• moja = one
• na = and
• tufaha = apple / apples
• mbili = two
• sokoni = at the market / in the market

So a very literal gloss would be something like:

Today morning, I-bought papaya one and apple two at-the-market.

In natural English, that becomes This morning, I bought one papaya and two apples at the market.

Nilinunua can be broken into parts:

• ni- = I
• -li- = past tense
• -nunua = buy

So:

ni + li + nunua = nilinunua = I bought

This is very typical Swahili verb structure:
subject marker + tense marker + verb stem

Because Swahili usually puts the subject inside the verb.

In nilinunua, the ni- already means I, so you do not need a separate pronoun.

You could add mimi for emphasis:

• Mimi nilinunua... = I bought... / It was I who bought...

But in a normal sentence, nilinunua by itself already tells you the subject is I.

Yes. Literally, leo asubuhi is today morning, but the natural English meaning is this morning.

This is a common Swahili way to express time. English and Swahili do not always package time expressions in exactly the same way.

You may also hear similar expressions such as:

• jana asubuhi = yesterday morning
• kesho asubuhi = tomorrow morning

It is a time expression, and Swahili often places time expressions near the beginning of the sentence.

So:

• Leo asubuhi, nilinunua... = This morning, I bought...

This sounds natural. But Swahili word order is flexible enough that you could also move the time expression later if the context allows.

For example:

• Nilinunua papai moja na tufaha mbili sokoni leo asubuhi.

That still makes sense, though the original version foregrounds the time more clearly.

In Swahili, numbers usually come after the noun they describe.

So:

• papai moja = one papaya
• tufaha mbili = two apples

This is the normal order.
English uses number + noun, but Swahili commonly uses noun + number.

In this sentence:

• papai moja means one papaya
• tufaha mbili means two apples

A useful thing to know is that some Swahili nouns, especially borrowed words, may not visibly change form between singular and plural in everyday usage. In a case like tufaha mbili, the number mbili makes it clear that more than one apple is meant.

Also, if you study noun classes later, you will learn that numbers can show agreement with noun classes. For now, the important practical point is:

• moja = one
• mbili = two
• the number after the noun tells you the quantity

Here, na means and.

So:

• papai moja na tufaha mbili = one papaya and two apples

Swahili na can also mean with in other contexts, so learners often notice that it has more than one use. In this sentence, though, it is simply joining two items in a list, so and is the right meaning.

Sokoni means at the market or in the market.

It comes from:

• soko = market
• -ni = a locative ending, often giving a meaning like in, at, or to

So:

• soko = market
• sokoni = at/in the market

This -ni ending is very common in Swahili place expressions.

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

So a noun like papai can mean:

• a papaya
• the papaya
• sometimes just papaya

The exact meaning depends on context.

That is why papai moja naturally translates as one papaya, without needing a separate word for a.

Yes. Swahili allows some flexibility, especially with time and place expressions.

For example, you could also say:

• Nilinunua papai moja na tufaha mbili sokoni leo asubuhi.
• Asubuhi ya leo, nilinunua papai moja na tufaha mbili sokoni.

These all communicate roughly the same idea.

The original sentence is natural and clear, and it puts the time first:

Leo asubuhi, nilinunua papai moja na tufaha mbili sokoni.