Nikienda posta, nitatuma barua kwa dada yangu.

Nikienda means if I go, when I go, or sometimes as I go, depending on context.

It breaks down like this:

• ni- = I
• -ki- = a marker used in dependent clauses, often giving a meaning like if, when, or while
• -enda = go

So nikienda is literally something like if/when I go.

Because Swahili usually puts the subject inside the verb itself.

In this sentence:

• ni-ki-enda = I
  • dependent marker + go
• ni-ta-tuma = I
  • future marker + send

So the ni- already means I.
You do not need mimi unless you want extra emphasis.

Nitatuma means I will send.

It breaks down like this:

• ni- = I
• -ta- = future marker, will
• -tuma = send

So nitatuma literally means I will send.

It can mean either one.

That is very common with -ki- forms in Swahili. The exact meaning depends on context:

• if I go to the post office, I will send a letter
• when I go to the post office, I will send a letter

If the broader context is uncertain or conditional, English may use if.
If the action is expected to happen, English may use when.

After verbs of motion such as go, Swahili often allows the destination to come directly after the verb.

So:

• kwenda posta = to go to the post office

Swahili does not have to use a separate word exactly matching English to here.

You may also hear more explicit location forms in other contexts, but kwenda posta is a normal and natural way to say go to the post office.

Because Swahili does not use articles like English a, an, and the.

So:

• posta can mean the post office or just post office, depending on context
• barua can mean a letter or the letter, depending on context

English requires an article, but Swahili usually does not.

Here barua means letter in the sense of a piece of mail.

So:

• nitatuma barua = I will send a letter

A useful thing to know is that many Swahili nouns do not change form between singular and plural in the way English does. In real use, context often tells you whether one or more is meant.

Kwa is used here to mark the recipient, so it means something like to.

So:

• kwa dada yangu = to my sister

In different contexts, kwa can also mean for, at, from, or by, but here the natural English translation is to because the sister is the person receiving the letter.

Dada yangu means my sister.

It is made of:

• dada = sister
• yangu = my

So the whole phrase is my sister.

In Swahili, possessives like my change form to agree with the noun they describe.

So the possessive does not always look the same across all noun classes.
Here, with dada, the correct form is yangu:

• dada yangu = my sister

This agreement is a normal part of Swahili grammar.

Swahili often puts the dependent clause first, just like English can:

• When/If I go to the post office, I will send a letter to my sister.

So:

• Nikienda posta = dependent clause
• nitatuma barua kwa dada yangu = main clause

This order is very natural and helps set up the condition or time frame before the main action.

The comma is helpful because the sentence begins with a dependent clause:

• Nikienda posta, nitatuma barua kwa dada yangu.

This is similar to English, where a comma is often used after an opening if/when clause.

In speaking, of course, you do not hear a comma; you just hear a slight pause.

Yes, Swahili has some flexibility, but the given order is very natural.

The sentence as written:

• Nikienda posta, nitatuma barua kwa dada yangu.

puts the if/when part first. That is a common and clear structure.

If you change the order, the emphasis may shift, and some versions may sound less natural depending on context. For a learner, the original sentence is a very good pattern to copy.

A more specific way is to use a form like nitakapokwenda or nitakapoenda, depending on style and structure.

For example:

• Nitakapoenda posta, nitatuma barua kwa dada yangu.

This is more clearly when I go to the post office.

By contrast, nikienda is more flexible and can mean if/when I go.

Yes. It is a very common Swahili pattern:

• Niki-... , nita-...
• If/When I ..., I will ...

For example:

• Nikifika nyumbani, nitakupigia simu. = When/If I arrive home, I will call you.
• Nikimpata mwalimu, nitamuuliza. = If/When I find the teacher, I will ask him/her.

So this sentence is not just one expression; it teaches a very useful grammar pattern.