Safu hii ni ndefu.

• safu = the noun, meaning row / line / column depending on context
• hii = this, pointing to something near the speaker
• ni = is
• ndefu = long / tall

So the structure is basically:

noun + this + is + adjective

In Swahili, demonstratives like this and that usually come after the noun, not before it.

So Swahili says:

• safu hii = this row / this line

not something like hii safu in normal neutral usage.

That is one of the most noticeable word-order differences from English.

Swahili uses noun classes, and words like this, that, and many adjectives have to match the noun’s class.

safu belongs to the N class here, so the correct form of this is hii.

Compare:

• safu hii = this row/line
• safu hizi = these rows/lines

So hii is not random; it agrees with safu.

ni is the copula here — basically the word that means is / are in sentences like this.

So:

• Safu hii ni ndefu = This row is long

It links the subject (safu hii) with the description (ndefu).

For a beginner, it is easiest to think of ni here as is.

In Swahili, adjectives often agree with the noun class, but with nouns like safu, the adjective may appear with no obvious change.

So:

• safu hii ni ndefu = this row is long
• safu hizi ni ndefu = these rows are long

Notice that ndefu stays the same in both.

This is normal for this noun class, and it is something learners just get used to by exposure.

No. Swahili normally does not use articles like English a/an/the.

So safu can mean:

• a row
• the row
• row

The exact meaning depends on context.

That is why Safu hii naturally means this row without needing a separate word for the.

You would change hii to hizi:

• Safu hizi ni ndefu = These rows/lines are long

Notice:

• safu stays safu
• hii changes to hizi
• ndefu stays ndefu

So the main visible plural change here is the demonstrative.

A simple pronunciation guide is:

SAH-foo HEE-ee nee nDEH-foo

A few notes:

• safu = SAH-foo
• hii has two vowel sounds: hi-i
• ni = nee
• ndefu begins with nd, said together: nDEH-foo

Swahili pronunciation is usually very regular, much more regular than English spelling.

Yes. Depending on context, safu can mean things like:

• row
• line
• column
• sometimes even an arranged layer or rank

So the exact English translation depends on what the speaker is talking about.

For example, in a classroom or spreadsheet context, safu might be understood differently.

Yes. It is a very normal and useful pattern:

noun + demonstrative + ni + adjective

For example:

• kitabu hiki ni kizuri = this book is good
• nyumba hii ni kubwa = this house is big
• safu hii ni ndefu = this row is long

So this sentence is a good model for making many other simple descriptive sentences in Swahili.