Mtoto alipolia, bibi aliimba wimbo wa watoto.

It is made of several pieces:

• a- = he/she (the subject marker for a singular person)
• -li- = past
• -po- = a time-related marker meaning when or at the time that
• -lia = the verb stem cry

So alipolia means when he/she cried or when the child cried.

A useful comparison:

• alilia = he/she cried
• alipolia = when he/she cried

Because both subjects are singular people:

• mtoto = child
• bibi = grandmother / old woman

In Swahili, singular human nouns usually take the subject marker a-.

So:

• a-li-imba = he/she sang
• a-li-po-lia = when he/she cried

The a- does not mean the same person each time. It just agrees with the subject of that verb.

Swahili usually does not use articles like English does.

So:

• mtoto can mean a child or the child
• bibi can mean a grandmother, the grandmother, or just grandma/grandmother, depending on context
• wimbo can mean a song or the song

Context tells you which one is meant.

Mtoto is gender-neutral. It can mean:

• child
• baby
• son/daughter in some contexts

By itself, it does not tell you whether the child is male or female.

No. Bibi can mean:

• grandmother
• grandma
• sometimes old woman or a respectful way to refer to an elderly woman

In this sentence, grandmother is the most natural interpretation.

Because wa is the connector that matches wimbo here.

• wimbo = song
• watoto = children
• wa = of / belonging to / associated with, agreeing with wimbo

So wimbo wa watoto literally means song of children, which in natural English is children's song.

This is a very common Swahili pattern:

• kitabu cha mwanafunzi = the student's book
• chakula cha watoto = children's food
• wimbo wa watoto = children's song

Because that phrase does not have to refer to the same one child.

Wimbo wa watoto means a children's song in a general sense: a song associated with children, sung by children, or meant for children.

If you wanted the child's song referring to one specific child, you would more likely say:

• wimbo wa mtoto

So the sentence is talking about a children's song, even though only one child is crying.

Yes, often it can.

Literally, it is children's song, but in real use that can mean:

• a song sung by children
• a song associated with children
• a song meant for children

If you want to say for children more explicitly, Swahili can also use kwa:

• wimbo kwa watoto = a song for children

But wimbo wa watoto is very natural for children's song.

Because the sentence needs a time clause:

• Mtoto alilia. = The child cried.
• Mtoto alipolia, ... = When the child cried, ...

So -po- is what turns the idea into when the child cried rather than just the child cried.

Yes. The time clause can come first or later.

These are both possible in meaning:

• Mtoto alipolia, bibi aliimba wimbo wa watoto.
• Bibi aliimba wimbo wa watoto mtoto alipolia.

However, the first version is often clearer and more natural for learners, because the when clause is neatly placed at the beginning.

You may also see speakers use an extra word like wakati for clarity:

• Bibi aliimba wimbo wa watoto wakati mtoto alipolia.

A simple pronunciation guide is:

MTO-to a-li-po-LI-a, BI-bi a-li-IM-ba WIM-bo wa wa-TO-to.

A useful rule for Swahili is that stress usually falls on the second-to-last syllable of a word.

So:

• mtóto
• alipolía
• bíbi
• aliímba
• wímbo
• watóto

Also, Swahili spelling is very regular, so words are usually pronounced much as they are written.