Selepas kena air, buku nota itu menjadi lembik dan sukar dibaca.

Yes, literally kena can mean to get affected by something, and in many contexts it has the sense of to get / to be subjected to.

So kena air means to get wet, to have water on it, or more literally to be affected by water. It is a very natural Malay expression.

In this sentence, Selepas kena air means after being exposed to water or after getting wet.

Both are possible, but they feel slightly different in tone and style.

• kena air is very common in everyday speech.
• terkena air is also correct and can sound a bit more explicit or slightly more formal, depending on context.

In casual Malay, speakers often prefer the shorter kena air.

So:

• Selepas kena air... = very natural, conversational
• Selepas terkena air... = also correct, a bit more marked

Selepas means after.

Yes, setelah and sesudah can also mean after. In many cases they are interchangeable, but there are small differences in style:

• selepas = very common in speech and writing
• setelah = common, sometimes a little more formal or narrative
• sesudah = also correct, often a bit more formal

So these are all possible:

• Selepas kena air...
• Setelah kena air...
• Sesudah kena air...

But selepas is a very natural choice here.

Itu means that, but in Malay it is also often used like the when referring to a specific thing already known from context.

So buku nota itu can mean:

• that notebook
• or simply the notebook, if the notebook is already understood

Malay does not have articles like a and the in the same way English does, so words like itu and ini often help show specificity.

Menjadi means to become.

In this sentence:

• buku nota itu menjadi lembik = the notebook became soft/soggy

You may hear jadi in casual speech, but menjadi is the standard verb form here.

Compare:

• menjadi lembik = became soft/soggy
• jadi lembik = common in speech, less formal

So menjadi is the safest and most standard choice in writing.

Lembik can mean soft, limp, floppy, or soggy, depending on context.

For a notebook after getting wet, lembik suggests that the paper has become:

• soft
• limp
• weakened
• soggy

So it does not just mean soft in a pleasant sense. It suggests the notebook has lost its firmness because of the water.

Because the meaning is difficult to be read or more naturally in English, difficult to read.

• dibaca is the passive form: be read
• membaca means to read as an active verb, with a reader doing the action

Here the subject is buku nota itu, so the idea is:

• the notebook is difficult to be read
• more natural English: the notebook is difficult to read

So:

• sukar dibaca = difficult to read
• sukar membaca = difficult to read something / difficult for someone to do the reading

That second one would not fit this sentence.

Yes. Dibaca is the di- passive form of baca (read).

• baca = read
• membaca = to read / reading
• dibaca = be read / being read

In sukar dibaca, the notebook is the thing receiving the action of reading.

This kind of structure is very common in Malay:

• mudah difahami = easy to understand
• sukar dilihat = hard to see
• senang digunakan = easy to use

So sukar dibaca is a very natural pattern.

Yes, you can.

• sukar = difficult
• susah = difficult / troublesome / hard

In many contexts they overlap. But there is a slight difference in feel:

• sukar often sounds a bit more neutral or formal
• susah often sounds more conversational

So both are possible:

• sukar dibaca
• susah dibaca

The original sentence sounds a little more polished because of sukar.

In Malay, it is very common to leave out information that is obvious from context.

Here, Selepas kena air literally means After getting wet / after being exposed to water. The thing that got wet is understood from the main clause: buku nota itu.

So even though the notebook is not repeated, listeners naturally understand:

• After getting wet, the notebook became soggy and hard to read

This kind of omission is very normal in Malay.

Yes. That is also grammatical.

Malay word order is fairly flexible in cases like this.

Compare:

• Selepas kena air, buku nota itu menjadi lembik dan sukar dibaca.
• Buku nota itu menjadi lembik dan sukar dibaca selepas kena air.

Both mean the same thing. The first version gives a little more emphasis to the condition or cause first: after getting wet.

Yes, buku nota is understandable and natural.

Depending on region and context, you may also hear:

• nota = notes
• buku catatan = notebook / notebook for writing notes
• buku nota = notebook

If you mean a physical notebook, buku nota works well here.

By itself, kena air just means came into contact with water / got wet. It does not automatically mean severe damage.

However, in this sentence, the following result makes the meaning clear:

• menjadi lembik dan sukar dibaca

Because the notebook became soft and hard to read, we understand that the water caused damage.

So the damage is not inside kena air alone; it is understood from the whole sentence.

Malay often does not use separate subject pronouns when the noun is already stated.

In English, you might say:

• After getting wet, the notebook became soggy and it was hard to read.

In Malay, once buku nota itu has been mentioned, there is no need for a separate it before menjadi. The verb simply continues with the same subject.

So:

• buku nota itu menjadi... = the notebook became...

That is completely normal in Malay.