Learn Hardcore Swahili: Kabla hujafungua simu janja yako, tafadhali maliza kifungu hiki cha kitabu. - Before you open your smartphone, please finish this paragraph of the book.

Both are correct. The pattern with huja- is extremely common in everyday speech when the subject is clear (you, he/she, etc.), while kabla ya + kufungua uses the infinitive and works more like a noun phrase (before the act of opening).

Is hujafungua negative? I thought hu- is a negative prefix.

Yes, hu- is part of a negative pattern:

huja- + verb = you have not yet done X

Outside the kabla structure, hujafungua would normally mean “you haven’t opened (it)”.

With kabla, this negative perfect is used idiomatically to mean “before you do X”, assuming the action has not yet happened:

Kabla hujafungua simu janja yako…
Literally: Before you have not yet opened your smartphone…
Idiomatically: Before you open your smartphone…

So yes, it is formally negative, but in this fixed pattern it translates as “before you do X”.

Where is the word “you” in Kabla hujafungua simu janja yako?

Swahili usually shows the subject in the verb prefix, not as a separate word.

In hujafungua:

hu- = second person singular (you) + negative
-ja- = perfect aspect (have)
-fungua = open

So hujafungua literally encodes “you have not opened” in one word. There is no need for a separate pronoun like wewe unless you want to emphasize you (e.g. for contrast).

What exactly does simu janja mean? Is it the standard term for smartphone?

Simu janja literally means “smart phone”:

simu = phone
janja = clever, cunning, smart (here: smart in the tech sense)

It is widely understood in modern Swahili to mean a smartphone.

Other common ways to say phone:

simu ya mkononi – mobile/cell phone (literally hand phone)
simu ya kisasa – modern phone (can imply smartphone in context)

But if you specifically want smartphone, simu janja is very natural and common, especially in East Africa.

Why is it simu janja yako and not simu yako janja?

In Swahili, the normal order inside a noun phrase is:

Noun + (adjectives) + (possessive)

So:

simu janja yako
= simu (phone) + janja (smart) + yako (your)
→ your smart phone / your smartphone

Putting the possessive yako before the adjective, as in simu yako janja, sounds wrong or at best very odd to native speakers. Stick to:

Noun + Adjective + Possessive → simu janja yako

What does kifungu hiki cha kitabu mean exactly, and how is it built?

Kifungu hiki cha kitabu means “this passage/section of the book”.

Breakdown:

kifungu – section, passage, paragraph, clause (Class 7 noun: ki-/vi-)
hiki – this (demonstrative agreeing with Class 7: ki-)
cha kitabu – of (the) book
- cha is the possessive “of” for Class 7 nouns
- kitabu = book (also Class 7, ki-/vi-)

So the structure is:

kifungu hiki – this section
kifungu hiki cha kitabu – this section of the book

Kifungu is smaller than sura (chapter); think paragraph or subsection in many contexts.

Why is it maliza kifungu hiki cha kitabu and not umalize kifungu hiki cha kitabu?

Both are grammatically correct, but the nuance differs:

maliza kifungu hiki cha kitabu
– bare imperative, direct: “finish this section of the book”
umalize kifungu hiki cha kitabu
– subjunctive with u-, often a bit softer or part of a longer sentence:
e.g. Tafadhali umalize kifungu hiki cha kitabu.

In your sentence, tafadhali maliza… combines:

tafadhali – please (polite marker)
maliza – imperative

So overall it feels like a firm but polite instruction:
“Please finish this section of the book before you open your smartphone.”

Using umalize would also be polite and is fully acceptable; the difference is subtle and often stylistic.

Why is it kifungu hiki cha kitabu and not kifungu hiki ya kitabu?

The “of” word (-a) in Swahili changes form to agree with the first noun’s class.

kifungu is Class 7 (ki-/vi-)
For Class 7, -a → cha

So:

kifungu cha kitabu – section of the book (correct)
kifungu ya kitabu – wrong, because ya is for Class 9/10, not Class 7.

Some other examples:

kitu cha mtoto – the child’s thing (Class 7 → cha)
vitabu vya watoto – children’s books (Class 8 → vya)

So cha is required here by noun class agreement.

Can I also say kabla ya kufungua simu janja yako instead of kabla hujafungua simu janja yako?

Yes, you can. Both are good Swahili:

Kabla hujafungua simu janja yako…
– Uses the huja- negative perfect construction; very common in speech.
Kabla ya kufungua simu janja yako…
– Uses kabla ya + infinitive; sounds a bit more “neutral” or textbook-like.

They both mean “before you open your smartphone”. The choice is mostly stylistic. In everyday conversation you will often hear the kabla huja- pattern, especially with a clear subject like you.