Ukiona damu kwenye plasta, badilisha plasta hiyo mara moja.

Ukiona is built from:

• u- = you (singular)
• -ki- = if / when
• -ona = see

So ukiona literally means if you see or when you see.

This -ki- form is very common in Swahili for instructions and conditionals.

Yes, u- is the subject marker for you (singular).

So this sentence is grammatically addressed to one person. In instructions, though, Swahili often uses the singular in a general way, like English instructions often use you.

If you were speaking to more than one person, you would usually say:

• Mkiona damu kwenye plasta, badilisheni plasta hiyo mara moja.

Here:

• m- = you all
• badilisheni = plural command

It can mean either, depending on context.

The -ki- tense often covers ideas like:

• if
• when
• whenever

In a medical or instructional sentence like this, English might translate it as either:

• If you see blood...
• When you see blood...

Both fit the Swahili structure.

Kwenye is a location word that can mean things like:

• on
• in
• at
• into

The exact English translation depends on context.

In this sentence, kwenye plasta means on the plaster / on the bandage.

This is normal in Swahili: one location word may cover several meanings that English separates more strictly.

Because Swahili and English do not divide space in exactly the same way.

English often prefers a very specific preposition like on, while Swahili often uses broader locative words such as kwenye. So kwenye plasta is a natural way to say on the plaster in this context.

A learner should not expect a one-to-one match between English prepositions and Swahili locative expressions.

Plasta is a loanword. Depending on context, it can refer to things like:

• a plaster
• an adhesive bandage
• a dressing

In a medical instruction like this, it usually means the covering placed on a wound, not building plaster.

So the exact English word can vary with context.

Swahili often repeats the noun for clarity, especially before adding a demonstrative like hiyo.

So:

• kwenye plasta = on the plaster
• plasta hiyo = that plaster / that bandage

English might sometimes avoid repetition, but Swahili is very comfortable with it.

Hiyo means that.

In Swahili, demonstratives normally come after the noun, not before it. So:

• plasta hiyo = that plaster
• not hiyo plasta

That word order is completely normal in Swahili.

Here, hiyo points back to the plaster already mentioned.

Hiyo is the demonstrative that matches the noun class of plasta.

Plasta behaves like a noun in class 9/10, so its demonstrative is:

• hii = this
• hiyo = that
• ile = that over there / that one yonder

So plasta hiyo is the grammatically matching form.

Yes. Badilisha is the singular imperative form, meaning:

• change
• replace

It comes from the verb kubadilisha = to change / to replace.

So badilisha plasta hiyo means change/replace that plaster.

If you were commanding more than one person, you would say:

• badilisheni

Because Swahili does not have articles like English a and the.

That means:

• damu can mean blood
• plasta can mean a plaster, the plaster, or just plaster/bandage

The exact meaning comes from context.

If Swahili wants to be more specific, it often uses things like:

• demonstratives, such as hiyo
• possessives
• context

Literally, mara moja is something like one time / one occasion.

But as an expression, it usually means:

• immediately
• right away
• at once

So in this sentence it gives urgency: the plaster should be changed without delay.

Yes, very natural.

It uses several common features of instructional Swahili:

• -ki- for a condition: ukiona
• an imperative command: badilisha
• a clear noun + demonstrative: plasta hiyo
• a time expression for urgency: mara moja

So it sounds like the kind of sentence you would find in medical advice, packaging instructions, or health guidance.