Tafadhali usichafue blauzi yako nyeupe kwa jamu.

Yes:

• Tafadhali = please
• usichafue = don’t stain / don’t dirty
• blauzi = blouse
• yako = your
• nyeupe = white
• kwa = with / by means of
• jamu = jam

So the whole sentence is a polite warning or request.

It is built into the verb usichafue.

In Swahili, commands usually do not need a separate subject pronoun. The idea of you is understood from the verb form itself.

Here, usi- shows a negative command to one person:

• usi-... = don’t you ...

So you do not need wewe unless you want extra emphasis.

It comes from the verb kuchafua, which means to dirty, to stain, or to make something dirty.

For a negative command to one person, Swahili commonly uses:

• usi-
  • verb stem + -e

So:

• kuchafua → usichafue

This gives the meaning don’t stain it / don’t make it dirty.

Because this is a negative command form.

The dictionary form of the verb is kuchafua, ending in -a. But in a negative command like don’t stain, Swahili normally changes the final vowel to -e.

So:

• dictionary form: kuchafua
• negative command: usichafue

You will see the same pattern in many other verbs, for example:

• kufanya → usifanye = don’t do
• kwenda → usiende = don’t go

Because kuchafua is a transitive verb: it means to make something dirty.

In this sentence, the thing being made dirty is blauzi yako nyeupe.

So the structure is basically:

• don’t dirty/stain
  • your white blouse

If you wanted the idea become dirty or get dirty, Swahili would usually use a different verb, such as kuchafuka.

Because in Swahili, modifiers usually come after the noun.

So instead of English order:

• your white blouse

Swahili uses:

• blouse your white
• blauzi yako nyeupe

That is normal Swahili word order. The noun comes first, and words describing it follow after it.

They agree with the noun blauzi.

Swahili nouns belong to noun classes, and words connected to the noun often change their form to match that class. Blauzi is treated as a class 9 noun in the singular.

So:

• possessive stem -ako becomes yako = your
• adjective stem -eupe becomes nyeupe = white

That agreement is why you do not see forms like wako or myeupe here.

Kwa jamu means with jam or by getting jam on it.

Here, kwa shows the substance or means that would cause the stain. It tells you what the blouse should not be dirtied with.

So the idea is:

• Don’t stain your white blouse with jam.

In this sentence, kwa sounds natural because it points to the thing causing the mess.

Tafadhali makes the command polite.

Without it, the sentence would still be grammatical:

• Usichafue blauzi yako nyeupe kwa jamu.

But adding tafadhali softens it, more like:

• Please don’t stain your white blouse with jam.

So it is still a command, just a more courteous one.

You would change the command and the possessive:

• Tafadhali msichafue blauzi zenu nyeupe kwa jamu.

Key changes:

• usi- → msi- = don’t (to more than one person)
• yako → zenu = your (plural, agreeing with plural blauzi)

Notice that blauzi itself often stays the same in form even when plural.

Blauzi is a loanword, meaning blouse.

Like many loanwords in Swahili, it often belongs to the N/N class (class 9/10), where the singular and plural can look the same.

So you can have:

• blauzi moja = one blouse
• blauzi mbili = two blouses

The noun itself may not change, but agreement words around it can change. That is why learners need to pay attention not only to the noun, but also to words like yako / zenu and adjective agreement.