Watoto walifurahi kumwona rubani akitabasamu kabla ya safari.

A helpful breakdown is:

• Watoto — children
• wa-li-furahi — they + past + were happy / became happy
• ku-mw-ona — to + him/her + see
• rubani — pilot
• a-ki-tabasamu — he/she + while + smiling
• kabla ya safari — before the journey / before the trip

So the sentence is built as:

[Children] [were happy] [to see the pilot] [smiling] [before the trip].

The singular is mtoto meaning child. The plural is watoto meaning children.

This is a common human noun pattern in Swahili:

• singular: m-
• plural: wa-

So:

• mtoto — child
• watoto — children

Because watoto is plural, the verb also has to show plural human agreement.

Walifurahi can be split into:

• wa- — subject prefix for they with human plural nouns
• -li- — past tense
• -furahi — be happy / be glad

So walifurahi means they were happy or they became happy.

If the subject were singular, you would get:

• mtoto alifurahi — the child was happy

After verbs like -furahi, Swahili often uses an infinitive to express what someone was happy to do.

So:

• walifurahi kumwona = they were happy to see him/her
• in this sentence, that him/her is the pilot

Kumwona breaks down as:

• ku- — infinitive marker, like to
• -mw- — object marker meaning him/her
• -ona — see

So it literally has the sense of to see him/her.

This is very common in Swahili, especially with a specific human object.

So kumwona rubani is literally something like:

to see him/her, the pilot

The object marker -mw- points forward to rubani. This often makes the object feel specific and clearly tracked in the sentence.

You may also hear kuona rubani, but kumwona rubani is very natural when the object is a particular person.

Because rubani is a human noun, and many human nouns borrowed into Swahili do not show the usual visible class prefix, but they still take normal human agreement.

So even though the noun is just rubani, the verb agrees with it as a singular human noun:

• a- — he/she

That is why you get:

• rubani akitabasamu — the pilot while smiling

not a non-human agreement form.

Akitabasamu is:

• a- — he/she
• -ki- — a marker often used for a linked action such as while, when, or sometimes if
• -tabasamu — smile

So akitabasamu means something like:

• while smiling
• as he/she was smiling

In this sentence, it gives a background or simultaneous action.

If you said anatabasamu, that would be a more independent statement meaning he/she is smiling.
But akitabasamu links the smiling more tightly to the main event of the sentence.

Because akitabasamu begins with a-, which is singular.

But watoto is plural, so if the children were the ones smiling, the verb would need plural agreement, not singular.

That makes rubani the natural subject of akitabasamu.

So the grammar itself tells you that the pilot is the one smiling.

Kabla ya is a very common expression meaning before.

It is best learned as a chunk:

• kabla ya + noun
• kabla ya + infinitive

Examples:

• kabla ya safari — before the trip
• kabla ya kuondoka — before leaving

So here, kabla ya safari works as a time expression telling you when this happened.

Swahili normally does not use articles like the and a/an.

So nouns such as:

• watoto
• rubani
• safari

do not need a separate word for the or a. Context tells you whether English should use the children, children, the pilot, a pilot, and so on.

That is why a Swahili sentence can be perfectly complete without articles.

Yes. This sentence follows a very normal pattern:

• subject: Watoto
• main verb: walifurahi
• infinitive complement: kumwona rubani
• linked descriptive action: akitabasamu
• time phrase: kabla ya safari

So the sentence is structured quite naturally for Swahili, even though some details, like the object marker in kumwona, may feel different from English.