Nilimwona mchumba wake akitembea polepole, kwa sababu kandambili zake zilikuwa mpya.

Nilimwona can be broken down like this:

• ni- = I
• -li- = past tense
• -mw- = him/her as the object
• -on- = root of see
• -a = final vowel

So Nilimwona means I saw him/her.

The object marker appears as -mw- here because it comes before a vowel in -ona. In other contexts, you may see the same object marker as just m-.

This is very common in Swahili. The object marker inside the verb can be followed by the full noun for clarity or emphasis.

So:

• Nilimwona = I saw him/her
• Nilimwona mchumba wake = I saw his/her fiancé(e)

The -mw- inside the verb agrees with mchumba wake. English usually would not repeat the object this way, but Swahili often does.

Mchumba usually means fiancé(e), betrothed person, or sometimes romantic partner / sweetheart, depending on context.

So it can be a little broader than English fiancé. In many learning examples, it is translated as fiancé(e), but in real usage it can also mean boyfriend/girlfriend or someone you are romantically committed to.

Because the possessive in Swahili must agree with the noun class of the thing possessed.

Here:

• mchumba is a class 1 noun
• the possessive stem is -ake = his/her
• with class 1, -ake becomes wake

So:

• mchumba wake = his/her fiancé(e)

You cannot use yake here, because yake belongs to a different noun class.

It can mean either his or her.

Swahili does not normally distinguish gender in third-person singular pronouns or possessives. So:

• wake = his / her
• zake = his / her (agreeing with a different noun class)

The exact meaning depends on context.

Akitembea means something like while walking, walking, or as he/she was walking.

It can be broken down as:

• a- = he/she
• -ki- = a marker often used for an action happening at the same time
• tembea = walk

So akitembea gives the idea of an ongoing accompanying action: he/she walking or while he/she was walking.

In this sentence, it describes what the fiancé(e) was doing when seen.

Because -ki- often works very naturally after verbs like see, find, hear, etc. when you want to describe an action in progress at the same time.

So:

• Nilimwona akitembea = I saw him/her walking
  • this is the most natural pattern here

If you used anatembea, it would sound more like a separate statement such as I saw that he/she is walking, which is less natural in this kind of sentence.

So akitembea is the better choice for saw ... walking.

Yes. Polepole is the normal adverb meaning slowly.

Although it looks like repetition, you should really learn polepole as a fixed common word/expression. It comes from pole, which is associated with slowness, gentleness, or carefulness, but polepole is the usual form for slowly.

So:

• akitembea polepole = walking slowly

Kwa sababu means because.

Literally, it is something like for reason or due to reason, but in normal English you should usually just translate it as because.

So:

• kwa sababu kandambili zake zilikuwa mpya = because his/her sandals were new

Because kandambili belongs to a noun class that takes class 10 agreement in this sentence.

That is why you see:

• za- in zake = his/her for that noun class
• zi- in zilikuwa = subject agreement for that noun class

So:

• kandambili zake = his/her sandals
• kandambili zake zilikuwa mpya = his/her sandals were new

This is a very important Swahili pattern: words around the noun must agree with its noun class.

The adjective -pya means new, and its form changes according to noun class.

With kandambili here, the correct agreeing form is mpya.

So:

• zilikuwa mpya = they were new

This may feel odd at first, because the adjective form does not always look obviously connected to the noun for English speakers, but it is just noun-class agreement.

In practice, kandambili is commonly treated with class 10 agreement, and in a sentence like this it is understood as sandals.

That is why the sentence uses plural-type agreement:

• zake
• zilikuwa

So the overall meaning is his/her sandals were new.

As with some Swahili nouns, the form itself may not change much between singular-looking and plural-looking uses, so the agreement often tells you how the noun is being treated.

Most likely, yes.

In this sentence, the natural reading is:

• mchumba wake = his/her fiancé(e)
• kandambili zake = that same person’s sandals

So the idea is: I saw his/her fiancé(e) walking slowly because his/her sandals were new.

However, purely grammatically, Swahili does not force them to refer to the same person. Context usually tells you.