Usipoweka mswaki karibu na sinki, unaweza kusahau kukata kucha zako kwa wakati.

Usipoweka is a negative conditional form, not a command.

It breaks down like this:

• u- = you (singular)
• -si- = negative
• -po- = conditional element, roughly if
• weka = put / place

So usipoweka means if you do not put or if you don’t place.

That is different from usiweke, which would mean don’t put as a negative command.

Swahili normally does not use articles like a, an, or the.

So:

• mswaki can mean a toothbrush or the toothbrush
• sinki can mean a sink or the sink

The exact meaning depends on context, not on a separate article word.

In Swahili, karibu often needs na before a noun when it means near.

So:

• karibu na sinki = near the sink
• karibu na mlango = near the door

Learners often notice that karibu can also mean welcome, so context matters a lot. In this sentence, karibu na is the location expression near.

Mswaki is generally a class 3 noun in the singular, with plural miswaki in class 4.

• singular: mswaki
• plural: miswaki

In this sentence, you do not see much agreement connected to mswaki, so you can understand the sentence without focusing heavily on the noun class. But it becomes important in other sentences, especially with adjectives and agreement:

• mswaki mpya = new toothbrush
• miswaki mipya = new toothbrushes

Unaweza comes from kuweza, meaning to be able.

It breaks down as:

• u- = you (singular)
• -na- = present tense
• weza = be able / can

So unaweza literally means you can or you are able to.

In this sentence, it expresses possibility, so in natural English it may come out as:

• you can forget
• you may forget
• you might forget

All of those are reasonable depending on the context.

The ku- form is the infinitive, like to forget or to cut in English.

Here is the structure:

• unaweza kusahau = you can forget
• kusahau kukata = to forget to cut

So the sentence has a chain of verbs:

1. unaweza = you can / may
2. kusahau = to forget
3. kukata = to cut

This is very normal in Swahili. After a verb like kuweza, the next verb is often an infinitive. Also, after kusahau, the action that is forgotten is commonly expressed with another infinitive.

Because in Swahili, possessives agree with the thing possessed, not just with the owner.

Here, kucha means nails and is plural. Because it is plural, your appears as zako.

So:

• kucha zako = your nails

A very important point is that -ako means your for one owner, but the beginning changes to match the noun class of the thing owned.

Compare:

• ukucha wako = your nail
• kucha zako = your nails

So zako is used because kucha is plural.

Kwa wakati is an expression that usually means something like:

• on time
• in time
• at the right time

It is better to learn it as a phrase rather than translating each word too literally. In many contexts, kwa wakati has the idea of doing something at the proper or expected time.

It is talking to one person.

You can tell from the subject marker u- in:

• usipoweka
• unaweza

Those forms are second person singular: you to one person.

The possessive also matches a singular owner:

• zako = your for one owner, agreeing with kucha

If you were talking to more than one person, you would use plural forms such as:

• msipoweka = if you all do not put
• mnaweza = you all can
• kucha zenu = your nails

Putting the conditional clause first is very common in Swahili, just as in English:

• Usipoweka mswaki karibu na sinki, unaweza kusahau...

This sets up the condition before the result.

Yes, the idea can be expressed with the result first and the condition later, but the version with the condition first is very natural and clear. Learners will often see this order in Swahili because it helps organize the sentence neatly:

• if X, then Y

So the sentence order is normal and not something unusual you need to worry about.