Weka mizigo ya mkononi vizuri, la sivyo itaanguka.

Weka is the singular command form of kuweka, which means to put, place, or set.

So here it means put/place ...

If you were speaking to more than one person, you would normally say wekeni instead.

Mizigo is plural. Its singular form is mzigo.

A useful thing to notice is that English often uses luggage as an uncountable noun, but Swahili commonly uses mzigo / mizigo as a normal singular/plural noun.

Literally, it is something like loads/bags of the hand or luggage for the hand.

In natural English, this refers to hand luggage, carry-on baggage, or things carried in the hand rather than checked in.

The connector ya agrees with mizigo.

In Swahili, words like of are not always translated by one fixed word. The connector changes to match the noun class of the noun before it. Since mizigo belongs to the mi- plural class, the correct connector here is ya.

So mizigo ya mkononi is a grammatically matching phrase.

Mkono means hand or arm.

When -ni is added, it often gives a locative meaning such as in, on, at, or by. So mkononi means something like in the hand, at hand, or by hand.

In this sentence, it helps create the idea of hand-carried luggage.

Vizuri means well, properly, or carefully.

It tells you how the action should be done:
Weka mizigo ya mkononi vizuri = Place the hand luggage properly / carefully.

That word order is normal in Swahili.

A very common pattern is:

verb + object + adverb

So:

Weka + mizigo ya mkononi + vizuri

This is a natural way to say Put the hand luggage properly.

La sivyo is a fixed expression meaning otherwise, if not, or or else.

It links the warning to the command:

• do this
• otherwise
• something bad will happen

So it works much like otherwise in English.

Because in Swahili, the subject is often built into the verb itself.

In itaanguka:

• i- = subject marker
• -ta- = future marker
• -anguka = fall

So the verb already contains the idea of it/they will fall, and Swahili does not need to repeat the noun again if it is already clear from the context.

Because Swahili verb agreement follows noun class, not English-style plural pronouns.

Mizigo is plural, but its noun class takes the subject marker i-. So:

• mizigo → class 4 plural
• class 4 subject marker → i-
• itaanguka = it/they of that noun class will fall

So even though English would say they will fall, Swahili correctly uses i- with mizigo.

Only the command would change:

Wekeni mizigo ya mkononi vizuri, la sivyo itaanguka.

Here:

• weka = command to one person
• wekeni = command to more than one person

The rest stays the same because mizigo is still the thing that will fall.