Learn Hardcore Malay: Ibu mencium hidung anak kecil itu kerana mulutnya penuh susu dan dia ketawa. - The mother kisses that small child’s nose because his/her mouth is full of milk and he/she is laughing.

As a common noun: ibu = a mother / the mother
As a way of address (like calling someone): Ibu (often capitalized) = Mum / Ma’am / Madam
To say my mother explicitly, you would usually say ibu saya.

In this sentence, with no saya, Ibu is best understood as the mother (or simply Mother in a story), not specifically my mother, unless the wider context says the speaker is the child.

The verb mencium can mean both to kiss and to smell. How do I know which one it is here?

mencium has two common meanings:

to kiss (a person or body part)
to smell (sniff something with your nose)

You work it out from the object and context:

With people or body parts, especially in affectionate contexts, it usually means to kiss:
- mencium hidung anak kecil itu → kissed the little child’s nose
With things that have a scent (flowers, perfume, food, clothes), it usually means to smell:
- mencium bunga → smell the flower
- mencium baju → smell the clothes

Because this is a mother and a small child in a cute situation, mencium hidung is naturally read as kissed [the] nose, not smelled [the] nose.

What exactly does hidung anak kecil itu mean, and why is there no word for of?

hidung anak kecil itu is a noun phrase. Literally, it is:

hidung = nose (head noun)
anak kecil = small child
itu = that

Malay usually shows possession and of-relationships by putting the owner after the thing owned, with no extra word like of:

hidung anak kecil itu = the nose of that little child
rumah guru itu = the house of that teacher / that teacher’s house
kereta abang saya = my older brother’s car

So hidung (nose) comes first, then the phrase that tells us whose nose it is: anak kecil itu (that little child).

Does itu refer to the nose or to the child in anak kecil itu?

itu is a demonstrative meaning that, and it attaches to the whole noun phrase before it, not just the last word.

Structure:

anak kecil = small child
anak kecil itu = that small child
hidung anak kecil itu = the nose of that small child

So itu is pointing to the child, not specifically to the nose.

What is the nuance of anak kecil? Why not just anak, kanak-kanak, or bayi?

Some related words:

anak = child / son / daughter (very general)
anak kecil = small child, little kid (highlights smallness/young age, often affectionate)
kanak-kanak = children (more formal/collective, as in taman kanak-kanak = kindergarten)
bayi = baby, infant

In this sentence, anak kecil suggests a little child, probably a toddler or very young kid, fitting the image of a messy, milk-covered mouth and laughing.

In mulutnya penuh susu, what does the ending -nya mean exactly? Is it his, her, or its?

The suffix -nya is a third-person possessive pronoun. It can mean:

his
her
its
sometimes their (singular group, context-dependent)

Malay does not mark gender in pronouns, so mulutnya can be his mouth or her mouth, depending on context.

If you needed to be clear, you could add a noun:

mulut anak kecil itu penuh susu = the little child’s mouth is full of milk
mulutnya, iaitu mulut anak perempuan itu, penuh susu = her mouth, that girl’s mouth, is full of milk

But normally -nya is enough; listeners get gender from the situation.

Why is there no word like is/was in mulutnya penuh susu?

Malay often omits a verb like “to be” when linking a subject to an adjective or a noun:

mulutnya penuh susu
- mulutnya = his/her mouth
- penuh = full
- susu = milk

So it literally feels like “the mouth-his full milk”, but it actually means:

His/her mouth is full of milk.
In other contexts it could also be was full or will be full, because there is no tense marking here; tense comes from context.

Using adalah is possible in some equational sentences, but not natural here. You would not normally say mulutnya adalah penuh susu in everyday Malay.

Could I say kerana mulut dia penuh susu instead of mulutnya penuh susu? What is the difference between -nya and dia?

Yes, you can say:

kerana mulut dia penuh susu

Both are grammatical and common. The differences are subtle:

mulutnya
- more compact, slightly more neutral or narrative in style
- the possessive is attached directly to the noun
mulut dia
- slightly more informal / conversational in many dialects
- can add emphasis on dia (that person) in some contexts

In this sentence, both mulutnya and mulut dia mean his/her mouth. Choice often comes down to speaker preference and style.

In dan dia ketawa, who does dia refer to: the mother or the child?

Grammatically, dia (he/she) could refer to either the mother or the child, because Malay does not show gender and does not automatically repeat the noun.

However, context and common sense guide interpretation:

The child’s mouth is full of milk.
It is more natural that the child is laughing while drinking milk.

So most readers will understand dia here as the child, not the mother.

If you wanted to be crystal clear, you could repeat the noun:

… kerana mulut anak kecil itu penuh susu dan anak kecil itu ketawa.
… because the little child’s mouth was full of milk and the little child was laughing.

What is the difference between ketawa, tertawa, and gelak?

All relate to laughing, but usage differs:

ketawa
- very common, neutral
- works in both spoken and written Malay
- verb: ketawa = to laugh
tertawa
- similar meaning, but can sound a bit more formal or literary in some regions
- used in writing and standard Indonesian more often
gelak / gelak ketawa
- more colloquial/informal
- gelak alone is very common in casual speech
- gelak ketawa emphasizes laughing a lot

In this sentence, dia ketawa is the straightforward, neutral he/she laughed / is laughing.

How do we know if this sentence is in the past or present tense?

Malay verbs do not change form for tense. mencium, penuh, and ketawa themselves do not say past, present, or future.

The time reference comes from context or time words:

present:
- Ibu mencium hidung anak kecil itu kerana mulutnya penuh susu dan dia ketawa.
- Mother kisses the little child’s nose because his/her mouth is full of milk and he/she is laughing.
past (if the story is clearly about the past):
- The same Malay sentence can mean:
  - Mother kissed the little child’s nose because his/her mouth was full of milk and he/she was laughing.

To make it explicitly past or future, you add time markers:

tadi, semalam, dulu (earlier, yesterday, before) for past
nanti, esok, akan (later, tomorrow, will) for future

The verb forms themselves stay the same.