Nilipoazima kitabu, niliandika jina langu kwenye rejesta.

Nilipoazima means when I borrowed.

It can be broken down like this:

• ni- = I
• -li- = past tense
• -po- = a relative marker that often gives the meaning when or at the time that
• -azima = borrow

So nilipoazima kitabu is literally something like when I borrowed the book.

Because the sentence does not just say I borrowed the book. It says when I borrowed the book, ...

• niliazima kitabu = I borrowed a/the book
• nilipoazima kitabu = when I borrowed the book

So the -po- adds the idea of when and turns that part into a time clause.

In Swahili, words like when are often built into the verb rather than written as separate words.

That is what happens here:

• nilipoazima = when I borrowed
• alipofika = when he arrived
• tulipomaliza = when we finished

So instead of adding a separate word before the verb, Swahili often changes the verb form itself.

Niliandika means I wrote.

It breaks down like this:

• ni- = I
• -li- = past tense
• -andika = write

So the main clause niliandika jina langu kwenye rejesta means I wrote my name in/on the register.

Because Swahili possessives agree with the noun class of the noun they describe.

• jina = name
• langu = my for the noun class of jina

So:

• jina langu = my name

Compare:

• kitabu changu = my book
• majina yangu = my names

English uses the same word my for everything, but Swahili changes the possessive form depending on the noun.

Here kwenye means something like in, on, or at, depending on the context.

So:

• kwenye rejesta = in the register / on the register

Because a register is a physical book or record where you write your name, English may use in or on, but Swahili commonly uses kwenye for that location.

Rejesta is a loanword, ultimately from English register.

In this sentence it means a register, record book, or logbook—the place where someone writes their name when borrowing something.

Loanwords are very common in Swahili, especially for administrative, technical, and modern items.

In most learner contexts, kuazima is best understood as to borrow.

So here:

• Nilipoazima kitabu = When I borrowed the book

If you want to lend, a common verb is:

• kukopesha = to lend

Also useful:

• kukopa often means to borrow, especially money or something taken as a loan

So a rough practical guide is:

• kuazima = borrow, often a physical item
• kukopa = borrow, especially as a loan
• kukopesha = lend

Yes, Swahili word order is somewhat flexible, but this version is very natural:

• Nilipoazima kitabu, niliandika jina langu kwenye rejesta.

Starting with Nilipoazima kitabu sets the time frame first, just like English When I borrowed the book, ...

You could move things around in some contexts, but this order is clear and idiomatic.

The comma separates the time clause from the main clause.

• Nilipoazima kitabu = subordinate time clause
• niliandika jina langu kwenye rejesta = main clause

This is similar to English punctuation in a sentence like:

• When I borrowed the book, I wrote my name in the register.

In informal writing, punctuation can be less strict, but the comma is normal and helpful here.